Gulf War Veterans: Incidence of Tumors Cannot Be Reliably Determined From
Available Data (Letter Report, 03/03/98, GAO/NSIAD-98-89).

Pursuant to a congressional request, GAO reviewed data on the incidence
of tumors among Gulf War veterans, focusing on: (1) the reliability of
data sources available for determining the incidence of tumors among
Gulf War veterans; and (2) the Department of Veterans Affairs' (VA) and
the Department of Defense's (DOD) use of data sources to monitor tumors
and other illnesses among Gulf War veterans.

GAO noted that: (1) none of the data sources that provide information on
the health characteristics of Gulf War veterans can be used to reliably
estimate the incidence of tumors; (2) VA's benefits information system
can track the vital status and causes of deaths among Gulf War veterans;
(3) however, not all cancers result in death and those that do may take
several years to show up; (4) as a result, the system will underreport
overall incidence; (5) DOD and VA maintain large hospitalization
reporting systems; (6) however, a large majority of Gulf War veterans do
not use DOD and VA hospitals and there has been little effort to
determine whether this hidden population has health conditions similar
to those of the population captured by the reporting systems; (7) DOD's
reporting system also does not account for outpatient medical care; (8)
VA has recently begun to fill this gap for its outpatient facilities,
but it may take several years before consistent and reliable reporting
is available; (9) a national cancer registry reports aggregate
population rates and trends but cannot be used to track the Gulf War
population; (10) DOD and VA health registries report information on the
type of health problems Gulf War veterans have experienced at the time
of their examination; (11) however, because not all veterans are
examined, the information collected cannot be used to estimate the
frequency of illnesses among all Gulf War veterans; (12) VA is
conducting a national survey to study the general health status of Gulf
War veterans; (13) the study uses representative samples of deployed and
nondeployed veterans; (14) however, the response rate to the survey has
been low and the study's sample size may be too small to asses any
elevated incidence of most cancers; (15) DOD and VA have initiated
efforts to improve the utility of these data systems but have not
developed the capability to specifically address questions about tumors
or other illnesses among Gulf War veterans; (16) as a result, it is not
known how many Gulf War veterans have tumors or whether they have a
higher incidence of them than other veterans; and (17) according to
agency officials, no other plans aside from periodic assessments of
mortality have been made to monitor tumor cases within this population.

--------------------------- Indexing Terms -----------------------------

 REPORTNUM:  NSIAD-98-89
     TITLE:  Gulf War Veterans: Incidence of Tumors Cannot Be Reliably 
             Determined From Available Data
      DATE:  03/03/98
   SUBJECT:  Chemical warfare
             Biological warfare
             Cancer
             Disease detection or diagnosis
             Military personnel
             Armed forces abroad
             Medical information systems
             Health surveys
             Statistical data
IDENTIFIER:  DOD Persian Gulf War Health Surveillance System
             Persian Gulf War
             VA Persian Gulf War Health Registry
             NCI Surveillance, Epidemiology, and End Results Program
             Desert Storm
             DOD Comprehensive Clinical Evaluation Program
             Gulf War Syndrome
             
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Cover
================================================================ COVER


Report to the Chairman, Subcommittee on Human Resources, Committee on
Government Reform and Oversight, House of Representatives

March 1998

GULF WAR VETERANS - INCIDENCE OF
TUMORS CANNOT BE RELIABLY
DETERMINED FROM AVAILABLE DATA

GAO/NSIAD-98-89

Gulf War Veterans

(713007)


Abbreviations
=============================================================== ABBREV

  BIRLS - Beneficiary Identification and Records Locator Subsystem
  DOD - Department of Defense
  VA - Department of Veterans Affairs
  SEER - Surveillance, Epidemiology and End Results

Letter
=============================================================== LETTER


B-278203

March 3, 1998

The Honorable Christopher Shays
Chairman, Subcommittee on Human Resources
Committee on Government Reform and Oversight
House of Representatives

Dear Mr.  Chairman: 

Numerous claims of illnesses from Gulf War veterans and inconsistent
reports on veterans' exposure to risk factors have prompted a number
of government studies on the nature, extent, and treatment of Gulf
War illnesses.  In June of last year, we reported to you and other
members of Congress that government research efforts may not be able
to provide conclusive answers about the causes of veterans' illnesses
and that several risk factors such as chemical and biological agents
had been ruled out prematurely as possible explanations for the
reported illnesses.  We also reported that many veterans were unhappy
with the quality of health care treatments they had received from the
Department of Veterans Affairs (VA) and that enhanced monitoring is
needed to determine if veterans are getting any better or worse over
time.\1

In your letter to us on June 12, 1997, you raised concerns about
whether Gulf War veterans have an increased risk of developing
certain cancers as a result of their exposures to hazards in the
Persian Gulf.  You asked us to examine pertinent data on the
incidence of tumors among Gulf War veterans and determine whether
these data indicate any differences in rates of tumors between Gulf
War veterans and appropriate comparison groups.\2 In this report, we
assessed (1) the reliability of data sources available for
determining the incidence of tumors among Gulf War veterans and (2)
VA's and the Department of Defense's (DOD) use of data sources to
monitor tumors and other illnesses among Gulf War veterans.  The five
types of data sources we reviewed were mortality data, medical
records, cancer registries, Gulf War veterans health registries, and
survey results. 

Although we sought to examine data sources that pertain directly to
tumors, many of the sources can also be used to assess other diseases
that may be associated with service in the Gulf War.  Because of
this, our findings concerning the strengths and limitations of these
data should be relevant to the broader issue of monitoring other Gulf
War illnesses as well.  In addition, it is important to point out
that several of the data sources we reviewed were not designed
specifically for medical research purposes but rather for other uses
such as veteran outreach or the administration of records. 


--------------------
\1 Gulf War Illnesses:  Improved Monitoring of Clinical Progress and
Reexamination of Research Emphasis Are Needed (GAO/NSIAD-97-163, June
23, 1997) and VA Health Care:  Observations on Medical Care Provided
to Persian Gulf Veterans (GAO/T-HEHS-97-158, June 19, 1997). 

\2 Neoplasms, or tumors, involve the unrestricted growth of tissue in
the body.  They can be either malignant (cancerous) or benign.  Some
benign tumors can also be life-threatening, such as brain tumors. 
Incidence is defined as the number of new cases during a given period
of time among those exposed to the risk of developing the disease and
is normally expressed as a rate. 


   BACKGROUND
------------------------------------------------------------ Letter :1

Following Iraq's invasion of Kuwait in August 1990, the United States
and other allied nations sent troops to the Persian Gulf region in
Operation Desert Shield.  In the winter of 1991, the allied forces
successfully attacked Iraq in an air campaign and subsequent invasion
by ground forces (Operation Desert Storm).  Approximately 700,000
American troops participated in these actions.  Although casualties
were relatively light, thousands of veterans have come forward
complaining of various illnesses, including cancer, in the years
following the war. 

During the Gulf War, American troops may have been exposed to several
known and potential health risks.  These included chemical and
biological warfare agents, depleted uranium from munitions, smoke
from oil-well fires, infectious diseases, pesticides, petroleum
fuels, and vaccines.  Some of these substances have been previously
associated with different types of cancer through animal laboratory
studies and other epidemiological research investigations.  For
example, combustion products from petroleum include polyaromatic
hydrocarbons, benzene, and carbon disulfide, some of which are known
to cause lung cancer when inhaled.  Exposure to certain pesticides
has also been linked to lymphatic and lung cancers.  In addition,
exposure to radioactive particles has been tied to higher rates of
respiratory and other cancers.  Information on exposures that took
place during the Gulf War, however, has been either incomplete or
nonexistent due to the lack of record keeping and measurement before,
during, and after the deployment of troops; loss of key records; poor
recall by veterans; and other factors. 

The development of cancer is usually characterized by a long latency
period of several years from an initial exposure to a harmful agent
to a definitive medical diagnosis.  Depending on the nature and
extent of the exposure, type of cancer, and characteristics of
different individuals, the latency period may be as long as 30 years
or more.  The most common types of cancers have a latency period of
15 years or more, but in certain situations cancer can develop more
quickly.  For example, when the immune system is compromised, such as
in cases of organ transplants, certain types of cancer may appear
within 1 year. 

Given that there is a lengthy latency period for most tumors, it may
be too soon to detect any increase in tumors occurring among Gulf War
veterans.\3

Also, since cancer is a relatively rare event,\4 large population
groups may need to be observed over several years to assess incidence
and determine whether it has changed over time.  Furthermore, without
credible exposure information, it is hard to form specific hypotheses
about what kinds of tumors might occur with what individuals. 
Although such constraints exist, it is nonetheless important to begin
monitoring and assessing whether Gulf War veterans are suffering from
an increase in tumors so that appropriate health care and treatment
can be provided where needed.  With many types of tumors, early
detection is important to more effective treatment outcomes. 


--------------------
\3 In 1996, the Persian Gulf Veterans Coordinating Board concluded
"the occurrence of some cancers among Persian Gulf Veterans, although
infrequent, has elevated concern over the possibility that these
cancers may be linked to service in the Persian Gulf." The Board,
though, also cited a 1994 Defense Science Board report that pointed
out that "because of the long latency period associated with cancer
originating from environmental causes, it is too early to evaluate
cancer risk in Persian Gulf veterans."

\4 The average age-adjusted incidence rate for all types of cancer
combined was 400 cases per 100,000 population in the United States in
1990-91 (National Cancer Institute, Cancer Rates and Risks 1996,
p.  17).  Among the age group that served in the Gulf War, incidence
is lower (fewer than 100 cases per 100,000 population for the ages
15-44). 


   RESULTS IN BRIEF
------------------------------------------------------------ Letter :2

None of the data sources that provide information on the health
characteristics of Gulf War veterans can be used to reliably estimate
the incidence of tumors.  Existing federal and state data systems are
generally limited by poor coverage of the Gulf War veteran population
and problems of reporting accuracy and completeness.  Following is a
summary of our assessment of each type of source: 

  -- VA's benefits information system can track the vital status and
     causes of death of Gulf War veterans.  However, not all cancers
     result in death, and those that do may take several years to
     show up.  As a result, the system will underreport overall
     incidence. 

  -- DOD and VA maintain large hospitalization reporting systems. 
     However, a large majority of Gulf War veterans (particularly
     those separated from the service) do not use DOD and VA
     hospitals, and there has been little effort to determine whether
     this hidden population has health conditions similar to those of
     the population captured by the reporting systems.  DOD's
     reporting system also does not account for outpatient medical
     care where more diagnosis and treatment of many types of tumors
     have been occurring in recent years.  VA has recently begun to
     fill this gap for its outpatient facilities, but it may take
     several years before consistent and reliable reporting is
     available. 

  -- A national cancer registry reports aggregate population rates
     and trends but cannot be used to track the Gulf War population. 
     Many available state registries could be used to identify Gulf
     War veterans, but the registries vary in terms of data quality
     and reporting consistency and coverage. 

  -- DOD and VA health registries report information on the type of
     health problems Gulf War veterans have experienced at the time
     of their examination.  However, because not all veterans are
     examined (participation is on a self-selected basis), the
     information collected cannot be used to estimate the frequency
     of illnesses among all Gulf War veterans. 

  -- VA is conducting a national survey to study the general health
     status of Gulf War veterans.  The study uses representative
     samples of deployed and nondeployed veterans.  However, the
     response rate to the survey has been low and the study's sample
     size may be too small to assess any elevated incidence of most
     cancers. 

DOD and VA have initiated efforts to improve the utility of these
data systems but have not developed the capability to specifically
address questions about tumors or other illnesses among Gulf War
veterans.  As a result, it is not known how many Gulf War veterans
have tumors or whether they have a higher incidence of them than
other veterans.  DOD and VA have recently funded a few research
studies that should provide additional information on tumor cases in
the future.  However, these studies are not the product of a
systematic effort to study the incidence of tumors, and limitations
to the studies will prevent them from providing reliable and valid
estimates of tumors among Gulf War veterans.  According to agency
officials, no other plans aside from periodic assessments of
mortality have been made to monitor tumor cases within this
population. 


   MORTALITY DATA
------------------------------------------------------------ Letter :3


      VA BENEFITS INFORMATION
      SYSTEM
---------------------------------------------------------- Letter :3.1

One source for estimating the incidence of cancer among Gulf War
veterans utilizes mortality as an indicator for incidence.  VA
maintains a large administrative database containing records of
claims for benefits made by veterans and their dependents.\5 This
database, the Beneficiary Identification and Records Locator
Subsystem (BIRLS), includes information on more than 40 million
individuals.  Although not designed as a research database, it does
contain information on the vital status of veterans and the location
of veterans' claim forms so that death certificates can be retrieved
to ascertain causes of death.  VA pays death benefits, including
fixed payments for burial and funeral expenses, to eligible survivors
of deceased veterans.  Dependents are required to submit a copy of
the veteran's death certificate in order to receive these benefits. 
The BIRLS datafile also contains the veteran's name, social security
number, claim number, current address, and other benefits
information.  In addition, the file includes a code that indicates
whether the veteran was deployed to the Gulf War. 

VA and other researchers have estimated that death reporting in the
BIRLS database is relatively complete in terms of its coverage of the
veteran population.\6 Studies using large samples of known deaths
have compared vital status reporting in BIRLS with reporting in other
national sources of mortality data, such as the Master Beneficiary
Record of the Social Security Administration and the National Death
Index, and found that BIRLS covers 80 to 90 percent of the deceased
veteran population.  Another strength of the BIRLS data is that they
provide a relatively cost-effective way to assess causes of death
among veterans.  Obtaining death certificates directly from state
health departments involves paying a fee of several dollars for each
certificate. 

Using BIRLS or other mortality databases to assess overall cancer
incidence has several key limitations.  First, mortality is a lagging
indicator of incidence.  The latency period for most tumors can be
more than
10 years and the period of time until mortality is even longer. 
Second, in general, mortality is an incomplete measure of cancer
incidence because cancer is not always fatal.  Mortality data provide
good estimates of incidence for cancers that have a high mortality
rate (such as lung and liver cancers) but they are less useful for
cancers with lower rates of mortality (such as prostate and breast
cancers).  Because of these limitations, mortality data will
systematically underreport overall cancer incidence.  In addition, by
the time cases show up in the data, it may be too late to help Gulf
War veterans.  Furthermore, while the reporting of external causes of
death, such as accidents, or broad disease categories, such as
coronary heart disease, is reasonably reliable, some inconsistencies
in cause of death reporting on death certificates have occurred. 
Death certificates are less accurate in tracking difficult to
diagnose diseases, deaths involving multiple causes, and where there
are underlying causes of death that are not readily discernible. 


--------------------
\5 Other databases containing records of deaths include the National
Death Index, administered by the National Center for Health
Statistics, and the Social Security Administration's Master
Beneficiary Record database.  The National Death Index contains
reports from the state offices that maintain death certificates.  The
Master Beneficiary Record database contains a record of individuals
whose benefits were terminated because of death. 

\6 Page, W.F.  et al, "Vital Status Ascertainment through the Files
of the Department of Veterans Affairs and the Social Security
Administration" Annals of Epidemiology, vol.  6 (1996), pp.  102-109;
Fisher, S.G.  et al, "Mortality Ascertainment in the Veterans
Population:  Alternatives to the National Death Index" American
Journal of Epidemiology, vol.  141 (1995), pp.  242-250. 


      USING VA'S BENEFITS
      INFORMATION SYSTEM TO ASSESS
      TUMORS AMONG GULF WAR
      VETERANS
---------------------------------------------------------- Letter :3.2

VA in one published study used data from BIRLS to assess the
mortality risk from a range of diseases (including cancer) for all
Persian Gulf veterans compared with a sample of veterans who were not
deployed to the Persian Gulf.\7 The study covered deaths occurring in
a 2-year period after the war (May 1991 to September 1993).  Death
certificates for those veterans who had been identified as having
passed away were obtained from VA regional offices and other
locations and were reviewed for cause of death.  The study found that
overall there was a small but significant excess of deaths among Gulf
War veterans (1,765 deaths) compared with nondeployed veterans (1,729
deaths) and that the excess was due mainly to accidents and not
disease.  Of the 1,765 Gulf War veterans who died during the study
period, 119 died from cancer, and there was no statistically
significant difference compared with the cancer death rate among
nondeployed veterans. 

If a higher death rate from cancer was expected among Gulf War
veterans as a result of some exposure occurring during deployment,
then they would be unlikely to appear in this study given the short
time period that elapsed.  VA is currently updating the study,
extending the study period through 1995, and the results should be
published later this year.  The study's authors identified another
limitation (but it is not clear what effect it had on the study's
findings)--specifically, whether the study's comparison groups were
appropriately matched.  Military personnel who were ill or recovering
from an illness would not have been deployed to the Gulf War area. 
However, these personnel were included in the comparison group of
nondeployed veterans.  This meant that the comparison group may have
been somewhat less healthy than the deployed veterans group.  The
extent to which a higher rate of prior illnesses among nondeployed
veterans resulted in a different rate of mortality (or cancer
mortality in particular) and thus biased the study findings is
unknown.  Finally, the use of broad comparisons between deployed and
nondeployed veterans rather than more targeted comparisons of
veterans based on specific types and levels of exposures may also
have affected the soundness of the study.  A comparison of deployed
and nondeployed veterans has merit for identifying potential
widespread and severe health consequences.  However, defining the
exposed population group as "all those who served in the Gulf War"
without regard to individual groups' exposure histories may obscure
some service-connected illnesses.  Efforts to exclude from such
studies portions of the deployed force who were at low risk of
exposure to harmful agents could lead to more meaningful results in
such comparative studies. 


--------------------
\7 Kang, H.K., and Bullman, T.A., "Mortality Among U.S.  Veterans of
the Persian Gulf War," New England Journal of Medicine, vol.  335
(1996), pp.  1498-1504. 


   MEDICAL RECORDS
------------------------------------------------------------ Letter :4


      DOD'S AND VA'S AUTOMATED
      HOSPITALIZATION REPORTING
      SYSTEMS
---------------------------------------------------------- Letter :4.1

DOD and VA each maintain an automated database containing medical and
demographic information on patients discharged from DOD and VA
hospitals.  DOD's system collects information from DOD military
hospitals.  These hospitals are open to active duty personnel and, to
a limited extent, retired personnel.  VA's data system, the Patient
Treatment File, covers all VA hospitals.  VA hospital care is
generally available to veterans for service-connected illnesses. 
Care is also provided on a discretionary basis for
nonservice-connected illnesses, depending on the availability of
facilities and resources and payment of a required co-payment by the
veteran.  Veterans who may have been exposed to a toxic substance or
environmental hazard while serving in the Gulf War are included in a
designated category of veterans who have special eligibility for VA
medical care services.  Both the DOD and VA data systems include
medical discharge diagnoses, which are coded according to standard
ICD-9 (International Classification of Diseases, 9th Revision)
disease categories.  In addition, the data contain relevant
information such as social security numbers, date and place of birth,
period of military service, length of hospital stay, and surgical and
other medical procedures conducted. 

DOD's and VA's hospitalization data systems are large and contain
millions of records, but they do not represent the entire active duty
and veteran population.  While DOD's data include most
hospitalizations of active duty personnel, in large part because DOD
medical care is free and readily available to active duty personnel,
there have been reports from some veterans' groups of Gulf War
veterans seeking medical care outside DOD.  According to these
groups, veterans have done so to obtain specialized care or because
of concerns that the acknowledgment of their illnesses within DOD
could have a negative effect on their military careers.  It is not
clear whether this would more often be the case for Gulf War veterans
with tumors than for nondeployed veterans. 

VA also has an extensive network of medical centers across the
country but the overwhelming majority of veterans use other private
and public hospitals.  A survey conducted by VA in the late 1980s,
estimated that only about 20 percent of veterans had ever used a VA
hospital.  With respect to Gulf War veterans, it is not known whether
there is greater or less use of VA medical facilities.  Since Gulf
War veterans have been authorized special eligibility for medical
care, there may be greater use of VA medical centers compared with
some other groups of veterans.  On the other hand, there have been
numerous accounts in the media and by veterans' groups of
dissatisfaction with government efforts to address Gulf War veterans'
health problems.  This may contribute to a greater reluctance among
some veterans to seek hospital care at VA medical facilities. 

Another weakness of the hospitalization data systems has been the
lack of coverage of outpatient medical care.  DOD currently has no
centralized reporting system for its outpatient facilities, although
an automated system is under development.  Until recently, VA did not
have an automated system either.  VA established an automated system
in October 1996 to begin collecting information on the use of its
outpatient facilities and the different types of medical care
provided.  Information is not available yet on the accuracy and
completeness of the reporting.  Coverage of outpatient facilities is
important because there is a current trend in the health field toward
outpatient diagnosis and treatment of many types of tumors. 

In addition to limitations in terms of population coverage, there are
also issues regarding the accuracy and completeness of
hospitalization data reporting.  One strength of the reporting
process is that standard disease categories are coded so that
comparable data can be collected from each hospital and more specific
types of diseases can be assessed.  Furthermore, the reporting allows
for multiple discharge diagnoses to be recorded and not just the
principal cause for hospitalization.  Miscoding of discharge
diagnoses, however, is a potential problem as shown by VA researchers
in previous assessments of certain types of cancer among Vietnam
veterans.\8 In a case-control study, for example, of over 400 Vietnam
veterans identified in VA's Patient Treatment File with a malignant
tumor of connective and other soft tissue, close to 40 percent of the
records were found to be miscoded or misclassified when hospital
pathology reports were subsequently collected and independently
reviewed by an expert pathologist.\9


--------------------
\8 Kang, H.K.  "Resources for Epidemiological Research in Vietnam Era
Veteran Populations Within the Department of Veterans Affairs"
Epidemiology in Military and Veteran Populations (Washington, DC: 
National Academy Press, 1991), pp.  97-103. 

\9 Kang, H.K.  et al, "Soft Tissue Sarcomas and Military Service in
Vietnam:  A Case Comparison Group Analysis of Hospital Patients"
Journal of Occupational Medicine, vol.  28 (1986), pp.  1215-1218. 


      USING DOD'S AND VA'S
      AUTOMATED HOSPITALIZATION
      REPORTING SYSTEMS TO ASSESS
      TUMORS AMONG GULF WAR
      VETERANS
---------------------------------------------------------- Letter :4.2


         VA TUMORS ANALYSIS
-------------------------------------------------------- Letter :4.2.1

In May 1996, VA completed an analysis requested by your Subcommittee
that provided some information on the number of tumors among Gulf War
veterans compared with the number in a sample of nondeployed
veterans.  The analysis sought to identify cases of tumors occurring
immediately after the war up through the early part of 1996. 
Existing VA databases, including the Persian Gulf Health Registry,
Patient Treatment File, and BIRLS, were used as means to identify
tumors.  A breakdown by type of tumor, age, gender, race, and branch
of service was conducted after merging the health registry and
hospitalization data records; however, these records were not
subsequently merged with the benefits records data (BIRLS) because
the diagnostic coding used in the two systems is different.\10

As reported by VA, based only on the combined health registry and
hospitalization data, the number of individuals with diagnosed tumors
was relatively low but the number of Gulf War veterans was
substantially higher as compared with nondeployed veterans (1,691 out
of 697,000 Gulf War veterans compared with 1,092 out of 1,605,087
nondeployed veterans).  Most of the tumors identified, though, were
benign and not malignant cancers.  Possible reasons for the higher
rate according to VA are that (1) priority eligibility status is
given to Gulf War veterans for inpatient treatment and (2) a special
health registry exists for Gulf War veterans.  In contrast to these
results, a larger number of diagnosed tumors was reported from the
benefits records data (BIRLS) but the number of cases among Gulf War
veterans was lower compared with the number among nondeployed
veterans (6,397 out of 697,000 Gulf War veterans compared with 21,227
out of 1,605,087 nondeployed veterans).  Thus, the different VA data
sources present a different result for tumor cases in these
population groups. 

VA has acknowledged that its analysis is quite limited because of
weaknesses in the existing data sources used.  A key limitation is
the poor coverage the data provide of the veteran population.\11
Veterans who use non-VA medical care facilities are excluded.  A
potential source for augmenting this is the use of the BIRLS data,
which in addition to reporting information on mortality claims
reports information on medical disability claims.  Veterans,
regardless of whether they receive medical treatment from VA or
elsewhere, can apply for disability claims.  BIRLS tracks denied and
approved claims, including those for disabilities associated with
tumors.  As a condition for qualifying for disability compensation,
it must be established that the disability is service-connected and
that the condition leading to the disability appeared either while
the veteran was on active duty or within a presumptive period after
separation from the service.  For most cancers, however, the
presumptive period is limited to 1 year.  In principle, BIRLS
includes other cases than those reported in the VA hospital reporting
system.  The major restriction to using the data to identify
illnesses among Gulf War veterans, though, has been the difficulty of
merging the claims records with other VA hospitalization records
because of the different diagnostic coding systems used.  The extent
to which a crosswalk could be developed to link the diagnostic codes
has not been determined. 


--------------------
\10 As discussed earlier, the VA hospitalization records data uses
the standard ICD-9 coding classification system.  The coding of
diagnoses in the benefits data is structured differently according to
parts of the anatomy. 

\11 Another potential weakness of the analysis is the use of large
denominators (all deployed and nondeployed personnel) for the
comparison.  As discussed earlier with respect to VA's mortality
study, this may mask certain service-connected illnesses. 


      POSTWAR HOSPITALIZATION
      EXPERIENCE STUDY
---------------------------------------------------------- Letter :4.3

A large DOD-funded study was published last year examining the
hospitalization experience of all active duty Gulf War veterans
compared with a sample of other active duty military personnel who
were not deployed to the Gulf region.\12 The purpose was to determine
whether participation in the Gulf War was associated with the
occurrence of serious illnesses requiring hospitalization.  Using
inpatient hospitalization data records obtained from DOD, the study
assessed hospitalizations occurring during the period August 1991
through September 1993.  Overall, the authors found there was no
excess in hospitalizations among Gulf War veterans compared with
other military personnel.  Among specific types of hospitalizations,
however, Gulf War veterans had higher rates in specific years for
tumors (in 1991), mental disorders (both 1992 and 1993), diseases of
the blood (in 1992), and diseases of the genitourinary system (in
1991).  For tumor cases reported in 1991, most involved benign
conditions and, although the rates were higher for Gulf War veterans,
the differences were not statistically different.  The one exception,
where a significant difference (higher rate) was found, was for
testicular cancer in 1991 hospitalizations.  The investigators
conducted a follow-on review of hospitalizations for testicular
cancer through March 1996 and found that male Gulf War veterans who
remained on active duty after the war were not at increased risk of
hospitalization for testicular cancer. 

A major strength of this study is its large size and statistical
power to detect differences in rates of hospitalizations between
deployed and nondeployed military personnel.  However, a key
limitation of the study, which influences the interpretation of the
results, is that hospitalizations of Gulf War veterans who separated
from the service as well as any hospitalizations of active duty
personnel who used non-DOD hospitals are excluded.\13

The number of hospitalizations excluded from the study is not known,
but the number of veterans who separated from the service increased
substantially since the end of the war.  According to DOD figures,
Gulf War veterans who remained on active duty declined to 66 percent
in 1993 and to below 50 percent by 1995.  Another important
limitation of the study is that the timeframe was far too short for
detecting any diseases resulting from possible exposures during the
war, such as tumors, which have lengthy latency periods.  Extending
the time period would address the latency issue, but then the problem
of missing hospitalizations would increase as the number of Gulf War
veterans remaining on active duty gets smaller over time. 

A related follow-up study is currently underway by the same
researchers, to examine hospitalizations of Gulf War veterans in
military and nonmilitary hospitals in the state of California.  This
study will merge hospitalization data from three sources:  DOD, VA,
and the state government.  California maintains a database of patient
hospital discharge information collected from nonfederally licensed
hospitals in the state (diagnoses are coded using the ICD-9
classification system).  The study will seek to identify all Gulf War
veterans who resided in the state at the time of or at least a year
prior to deployment.  Internal Revenue Service files will be matched
with DOD's roster of 697,000 Gulf War veterans to identify those
residing in the state (estimated to be about 12 percent of the Gulf
War force), and the resulting resident file will then be matched with
the various hospital data files to identify hospitalizations for each
veteran.  Although the study results will probably not be
generalizable to the entire Gulf War population, the study is large
and one of the first to systematically combine military and
nonmilitary hospitalizations.  The study period is longer (1991-95);
however, the problem of detecting diseases with a lengthy latency
period is still an issue, and outpatient data will be excluded. 
Currently, the study is in the initial data merging phase and is not
expected to be completed until 1998 or later. 


--------------------
\12 Gray, G.C.  et al, "The Postwar Hospitalization Experience of
U.S.  Veterans of the Persian Gulf War," New England Journal of
Medicine, vol.  335 (1996) pp.  1505-13. 

\13 In the Gulf War, 17 percent of the deployed forces were from
National Guard or Reserve units.  After the war, these personnel
returned to non-active duty status.  Hospitalizations in this group
would occur at non-DOD hospitals. 


   CANCER REGISTRIES
------------------------------------------------------------ Letter :5


      NATIONAL AND STATE
      REGISTRIES
---------------------------------------------------------- Letter :5.1

Another source for estimating the incidence of cancer is the
population-based cancer registries along with other baseline
demographic data.  Cancer registries are compilations of reports of
cancer cases that are filed by medical facilities (typically
hospitals) on an ongoing basis according to prescribed data coding
procedures.  Cancer registries can be effective tools for determining
incidence rates and for directing cancer control efforts.  Typically
they are used to identify and monitor trends, patterns, and
variations in cancer incidence and mortality by geographic location,
ethnicity, gender, and age. 

Cancer registries exist at the national, state, and local level.  The
national cancer registry (the Surveillance, Epidemiology and End
Results [SEER]) was established in 1973 by the National Cancer
Institute.  SEER collects data from designated cancer registries that
operate in various areas of the country.  Currently, it covers a
group of five states and four metropolitan areas that were selected
for "their ability to operate and maintain a population-based cancer
reporting system and for their epidemiologically significant
population subgroups."\14 Most states also maintain cancer
registries.  In 1992, Congress enacted the National Program of Cancer
Registries (P.L.  102-515), which authorized the Centers for Disease
Control and Prevention to fund states to improve existing cancer
registries and develop registries where they do not exist.  In 1996,
41 funded states were collecting statewide cancer data.  The Centers
for Disease Control and Prevention has set standards for reporting
accuracy, timeliness, and completeness.  However, some differences
exist across states in the level and quality of reporting.  Voluntary
reporting is also encouraged from DOD and VA hospitals.  In addition
to these registries, DOD administers its own cancer registry (the
Automated Central Tumor Registry) for active duty troops and others
(i.e., retirees and family members) who use DOD military medical
facilities.  It was set up as a central registry in 1986 to compile,
track, and report cancer patient information from military medical
treatment facilities. 

SEER is a comprehensive system for tracking cancer incidence for the
general population and key subgroups.  In addition, provisions are
made for quality assurance checks on data reliability.  However, in
terms of its suitability for assessing cancer rates in Gulf War
veterans, SEER only collects and reports aggregate information and
does not include the necessary individual-level identifiers that
would be needed to distinguish Gulf War veterans.  SEER can provide
incidence rates for the general population and key population
subgroups but not for the Gulf War veteran population. 

Many of the state registry systems generally do include individual
identifiers such as social security numbers, so a match against a
roster of Gulf War veterans, using common identifiers, could be
conducted to identify cancer cases within this group.  Such a match
of course would need to address potential confidentiality issues
involving the privacy of cancer patient information.  The accuracy,
timeliness, and completeness of reporting also varies by state
registries.  For example, many states only require reporting by
hospitals and do not capture cases diagnosed by private physicians,
laboratories, and health maintenance organizations.  Many of the
registries also have different data field structures and are not
designed to be readily merged with other registries. 

DOD's central tumor registry contains over 188,000 records of current
and past cancer patients.  While the reporting system is designed to
capture all cancer cases treated at DOD medical facilities, DOD
officials have indicated that complete reporting is not occurring. 
No systematic assessment has been conducted to measure how complete
the reporting is, and no quality assurance system is in place to
ensure that reporting is being done. 


--------------------
\14 Connecticut, Iowa, New Mexico, Utah, Hawaii, Detroit, San
Francisco, Seattle-Puget Sound, and Atlanta. 


      USING CANCER REGISTRIES TO
      ASSESS TUMORS AMONG GULF WAR
      VETERANS
---------------------------------------------------------- Letter :5.2

VA has provided initial funding to the Boston Environmental Hazards
Center to assess cancer incidence among Gulf War veterans in New
England.  The Center previously examined cancer incidence among
Vietnam veterans and will employ a similar methodology for looking at
Gulf War veterans.\15 The approach entails developing a roster of
Gulf War veterans and linking it (by identifying information such as
names, dates of birth, and social security numbers) with cancer cases
that appear in the state registries.  The first phase of the study
has been funded to create a roster of Gulf War veterans in the New
England area and develop a framework for merging data together from
the individual state registries.  The next phase of the study, to
begin by 1999, will involve an assessment of cancer incidence and
mortality.  The study design notes that it would not be informative
to analyze cancer incidence sooner because the time interval between
any exposures that may have occurred during the Gulf War and the
diagnosis of most cancers is "probably at least 10 years and may
extend as long as 20 to 40 years." It is also intended that these
health outcomes be linked to information about potential
environmental exposure factors that may exist or become available
from DOD military records and other sources, including the location
database being compiled by the U.S.  Army Center for Health Promotion
and Preventive Medicine. 

Although this study is several years away from completion, it appears
to provide a useful means for obtaining information about cancer
incidence in the future.  Some of the strengths of the study are that
it will use existing data systems, identify and assess a large cohort
of Gulf War veterans, and can be readily updated over time.  One key
limitation of the study, however, is that the results will not be
generalizable to the entire Gulf War population since only the New
England states will be included.  Also, it is not known whether there
is complete reporting of cases to the registries, particularly with
respect to cases diagnosed outside of the hospital setting and cases
from border areas that may get reported in other state registries
outside the New England area. 


--------------------
\15 Clapp, R.W.  et al, "Cancer Surveillance of Veterans in
Massachusetts, USA, 1982-1988," International Journal of
Epidemiology, vol.  20 (1991), pp 7-12. 


   GULF WAR VETERAN HEALTH
   REGISTRIES
------------------------------------------------------------ Letter :6

Both DOD and VA have established separate programs that provide
medical examinations and diagnostic services, free of charge, to Gulf
War veterans.  VA began its Persian Gulf Health Registry Examination
Program in 1992, and DOD started its Comprehensive Clinical
Evaluation Program in 1994.  The programs are open to all active
duty, separated, and retired military personnel who were veterans of
the Persian Gulf deployment.  An existing health problem is not
necessary for participation in the programs; any Gulf War veteran
with health questions or concerns is eligible to enroll on a
voluntary basis.  Currently, the programs are designed to follow a
standard protocol that requires registry physicians to obtain a
detailed medical history, conduct a physical examination, and order
basic laboratory tests.  Further diagnostic procedures and referral
to specialized medical centers are available for veterans with health
problems that cannot be satisfactorily diagnosed from the initial
evaluation.  As of April 1997, approximately 66,000 veterans
completed VA's registry examination, and over 31,000 veterans
completed DOD's examination. 

While the registry programs are primarily intended to provide
diagnostic services and treatment to Gulf War veterans, the programs
also gather and report data on the nature of the veterans' health
problems and the types of risk factors veterans may have been exposed
to in the Gulf War.  The most common symptoms reported among veterans
examined include fatigue, skin rashes, muscle and joint pain,
headaches, and memory loss.  Approximately 80 percent of the veterans
with symptoms have been diagnosed with one or more recognizable
diseases; however, the other 20 percent with symptoms remain
undiagnosed.  Diseases involving musculoskeletal and connective
tissue, psychological conditions, and the respiratory system were
diagnosed most frequently.  The number of registry veterans with a
primary diagnosis of a malignant or benign tumor is very small, less
than 1 percent. 

The suitability of the registries for assessing cancer incidence is
extremely limited.  As designed, the registries are not intended to
be used to determine the frequency and causes of illnesses among the
general Gulf War veteran population.  A principal reason for this is
that the participants volunteered for their examinations and were not
selected based on a random sample (selection bias).  Therefore, there
is no way to know whether the health problems found among the
registry participants are similar to those of the general population
of Gulf War veterans.  In addition, because there is no ready
comparison or control group for the registry participants, there is
no means to interpret the significance of the data that are reported. 
A further limitation of the registry data is that they capture
information about the health of veterans only at one point in time. 
Thus, if a veteran develops cancer or another illness later on, the
registry data will not reflect this. 

Data quality concerns also have been raised in a previous review of
the VA registry by the Institute of Medicine.  The Institute found,
for example, that there was a considerable delay between the
collection of the examination data and their entry into the registry
database.\16 In other ongoing work we are conducting on the quality
of health care Gulf War veterans are receiving, we also found that VA
medical facilities have not reported registry examination information
consistently.  It appears that a large number of case records
submitted for input into the registry database have been rejected and
sent back to the medical facilities due to coding errors.  At the
same time, effective quality assurance procedures have not been in
place to ensure that rejected records are corrected and reentered
into the database.  Thus, data coverage even for those who
participated in the registries has been incomplete. 


--------------------
\16 Institute of Medicine Health Consequences of Service During the
Persian Gulf War:  Initial Findings and Recommendations for Immediate
Action 1995. 


   SURVEY DATA
------------------------------------------------------------ Letter :7

Another data approach involves developing information about incidence
by using survey methods, such as administering a questionnaire to a
sample of veterans.  As opposed to the other approaches, which employ
data from databases administered by federal or state agencies, the
researcher has more control over the data that are being gathered. 
Specifically, the researcher could ensure that the data are
representative of the overall population of Gulf War veterans. 

Significant advantages to using the survey approach include the
ability to draw a random sample of Gulf War veterans and a comparison
group
(e.g., veterans who had not deployed to the Gulf War region).  A
survey also permits the researcher to gather other information, such
as information about exposures and family history, that might shed
light on the etiology of disease. 

Limitations with this approach include the possibility of response
bias (individuals who complete the survey not being representative of
the sample as a whole) and the subjectivity of self-assessments. 
There are standard ways of dealing with these limitations.  The
problem of response bias can be dealt with first by sending out
multiple questionnaires.  The extent to which response bias is a
factor can be estimated through a special survey of nonrespondents,
which is typically conducted by telephone.  The results of the
nonrespondent survey are compared against the results of the
principal survey to gauge the degree to which respondents are typical
of the overall sample.  Subjectivity of the assessments of cancer can
also be gauged to a degree through an independent medical review of a
subsample of respondents.  In addition, subjectivity of assessments
is somewhat less of a concern in terms of tumors than many other
illnesses. 

Also, care needs to be taken to ensure that the size of the sample is
large enough to characterize with confidence differences between the
Gulf War veteran and the comparison groups.  Tumors that have a low
background incidence would need to be studied with extremely large
sample sizes to detect an elevated incidence among Gulf War veterans. 
Sample sizes required to draw conclusions would need to be determined
at the earliest stages of the study. 

A further concern in implementing large population surveys is that
they tend to be much more costly than the other approaches being
presented here.  In addition, the type and number of questions must
be restricted or people will not respond. 


      VA NATIONAL SURVEY
---------------------------------------------------------- Letter :7.1

This approach is being employed by VA to study the general health
status of Gulf War veterans.  The National Health Survey of Persian
Gulf War Era Veterans uses a mailed survey to compare self-reported
symptoms and illnesses between a random sample of 15,000 Gulf War and
15,000 nondeployed veterans.  The questionnaire includes a checklist
of illnesses, including skin cancer and "any other cancer" and a
checklist of symptoms such as "coughing" and "skin rashes." In
addition to questions about current health status, respondents are
also asked to report about their exposure to a list of agents
including nerve gas, depleted uranium, and smoke from oil well fires
while they were in the Gulf War region. 

The overall response rate to the survey has been relatively low (57
percent).  VA is conducting a survey of nonrespondents in order to
evaluate nonresponse bias.  VA is also addressing the limitation
imposed by subjective assessments through an independent review of
medical records and "comprehensive physical examination" of a
subsample of 2,000 respondents (1,000 in each of the Gulf War veteran
and nondeployed veterans groups). 

The sample size of VA's survey may also be too small to identify
elevated incidence of most cancers.  With respect to the issue of
statistical power, VA has acknowledged that, "the study may provide
inadequate statistical power to detect a small increase in risk for
rare adverse health outcomes in a particular subgroup of veterans."

In 1996, the Institute of Medicine concluded, "This is a
well-designed and well-intended study." According to the Institute,
however, "there appeared to be little statistical input in the
analysis plan reviewed, and these data will require sophisticated
statistical adjustment."


      IOWA STATE SURVEY
---------------------------------------------------------- Letter :7.2

A population-based survey to assess the prevalence of self-reported
symptoms and illnesses among Gulf War veterans was also conducted in
Iowa.\17 The study used a telephone interview approach to survey a
random sample of Gulf War and non-Gulf War veterans from Iowa. 
Approximately 3,700 veterans were interviewed during the period
September 1995 through May 1996.  Overall, the study found that Gulf
War veterans reported a significantly higher prevalence of a wide
range of medical and psychiatric conditions compared with military
personnel who were not deployed to the Gulf War.  The primary
conditions where differences were reported include depression,
posttraumatic stress syndrome, chronic fatigue, cognitive
dysfunction, and respiratory diseases.  The rate of cancer reported
among these Gulf War veterans was generally low (an estimated rate of
about 1 per 100 subjects), but it was slightly higher than that of
the comparison group. 


--------------------
\17 The Iowa Persian Gulf Study Group, "Self-Reported Illness and
Health Status Among Gulf War Veterans," Journal of the American
Medical Association, 277 (1997), 238-245.  This study was supported
by the Iowa Department of Public Health, University of Iowa, and the
National Center for Environmental Health, Centers for Disease Control
and Prevention, Atlanta. 


   CONCLUSIONS AND RECOMMENDATION
------------------------------------------------------------ Letter :8

No direct link has been established between potential exposures that
occurred during the Gulf War and the development of tumors among
veterans.  However, concerns have been raised because many of the
exposure agents in question have previously been associated with
certain cancers.  This has led to interest in determining if the
cancer incidence rate among Gulf War veterans is higher than the
rates within other appropriate comparison groups.  If there is a
higher incidence that identifies an emerging health problem, then
outreach efforts could be conducted to target appropriate diagnosis
and treatment to those potentially at risk. 

Due to the long latency period of most tumors, it may be too soon to
detect whether there is an increased incidence of tumors among Gulf
War veterans.  Nonetheless, it may be important to collect
information now and begin planning for monitoring the future health
status of veterans.  However, the existing data sources and research
applications we reviewed, provide very limited information about the
incidence of tumors or other illnesses among Gulf War veterans. 
Federal research studies that are currently underway to assess tumors
should help fill the gap, but these studies are limited in terms of
their coverage of the Gulf War veteran population, data quality, and
timeliness.  Thus, it will also be difficult to determine whether
Gulf War veterans have a higher incidence of tumors than other
veterans in the future. 

In our June report of last year,\18 we found that DOD and VA had no
effective means to determine whether ill Gulf War veterans were
getting better or worse over time and recommended that DOD and VA
develop a plan to monitor their medical progress.  This
recommendation was effectively incorporated into the recently enacted
National Defense Authorization Act for Fiscal Year 1998, as part of a
broader initiative requiring the Secretaries of Defense and Veterans
Affairs to monitor health care services and treatment to Gulf War
veterans.\19 In response to this, DOD and VA have asked the Institute
of Medicine to establish a committee of experts to assess the
appropriate methodology for monitoring health outcomes.  However, the
ability to monitor veterans' health conditions may be seriously
handicapped by the data constraints we have noted in this report. 

In order to evaluate more effectively the incidence of tumors and
other Gulf War illnesses over time, we recommend that the Secretaries
of Defense and Veterans Affairs continue to strengthen existing
monitoring capabilities.  Attention should be directed toward
improving the utility of existing data systems and particularly in
developing cost-effective ways to make data systems more compatible
with one another so that information from different sources can be
linked.  In addition, steps should be taken to address the data
quality concerns we identified in this report.  While we believe such
improvements can lead to more effective monitoring capabilities, the
existing data systems may be insufficient to answer the question
about cancer incidence or other illnesses among Gulf War veterans. 
Therefore, further research efforts will be needed to supplement the
available data systems.  For example, little is known about the
health status of veterans who receive medical care from sources other
than DOD and VA facilities.  Practical approaches should be developed
to determine whether there may be emerging health problems among
these veterans. 


--------------------
\18 Gulf War Illnesses:  Improved Monitoring of Clinical Progress and
Reexamination of Research Emphasis Are Needed (GAO/NSIAD-97-163, June
23, 1997). 

\19 Section 762 of Public Law 105-85, November 18, 1997.  In
addition, the House Appropriations Committee, in its report on the
Department of Veterans Affairs Appropriations for Fiscal Year 1998,
recommended that DOD and VA develop and implement a plan for
monitoring the health of Gulf War veterans (H.R.  Rep.  No.  105-175
at pages 15-16, 1997). 


   AGENCY COMMENTS AND OUR
   EVALUATION
------------------------------------------------------------ Letter :9

DOD provided written comments on a draft of this report (see app. 
I), and VA provided oral comments.  Generally, DOD and VA concurred
with our overall findings regarding the inadequacies of existing data
systems for assessing tumors among Gulf War veterans and our
recommendations to improve monitoring capabilities.  They emphasized
that our recommendations support initiatives they currently have
underway to strengthen health information reporting systems and the
transfer of data between the two agencies.  According to DOD, these
actions are part of a long-term effort it is working on to develop a
comprehensive system for maintaining medical records of all illnesses
and injuries that military personnel may suffer, the care they
receive, and their exposure to different hazards.  DOD noted a key
objective of this work is to apply lessons learned from the Gulf War
experience to improve necessary medical surveillance and record
keeping for future military deployments.  While we recognize that
DOD's efforts will likely improve the utility of these data systems
to some extent, we are concerned that they will continue to be
insufficient to assess Gulf War illnesses such as tumors. 

DOD and VA were concerned about references in the report to illnesses
other than cancer.  They noted the report does a good job in
highlighting the strengths and weaknesses of the data sources
available for assessing the incidence of tumors among Gulf War
veterans, but that it does not include a comparable review of other
non-cancer health information systems or research studies that may
exist.  We modified the report title and some language to clarify the
scope of our work, where appropriate.  However, we continue to
believe that our findings regarding the key data sources discussed in
this report, with the exception of the cancer registry reporting
systems, are applicable to assessing other illnesses that may be
associated with Gulf War veterans.  For example, the lack of
outpatient data affects the reporting of many types of illnesses, not
just tumors.  Although there are other research studies underway to
investigate different symptoms and illnesses in the Gulf War veteran
population, we are unaware of any other government data reporting
systems that provide a means to assess illnesses in this population. 

VA officials also questioned statements we made in the report
highlighting the importance of collecting baseline information on
tumor incidence among Gulf War veterans at this time.  They believe
that available research information, which has shown a lack of any
increase in cancer mortality or hospitalization rates among Gulf War
veterans, does not support investing in further monitoring, given
other Gulf War research priorities.  VA contends that the usefulness
of such baseline information is negligible for future research
efforts because any future rates of tumors would need to be compared
with military and general population controls from the same time
period.  While we agree that such comparisons are important, the
existing research information on tumor incidence in the Gulf War
population is quite limited and, therefore, cannot be used as a basis
to say there is no increased rate in tumor cases.  Tracking incidence
over time is also important in order to assess whether the number of
new cases is occurring at a similar or different rate than a
comparison group of veterans. 

DOD also made the point that establishing a national cancer registry
with standardized reporting of cancers across the nation, would
address many of the data problems noted in our report and be of use
in assessing military and nonmilitary populations.  A recommendation
for establishing such a reporting system was beyond the scope of our
work. 

DOD and VA also provided technical comments, which we incorporated
where appropriate. 


   SCOPE AND METHODOLOGY
----------------------------------------------------------- Letter :10

The focus of our work was to identify and assess available data
sources and federal research initiatives to estimate the incidence of
tumors among Gulf War veterans.  To address these objectives, we
reviewed relevant literature and agency documents and collected
information directly from agency officials and selected outside
experts.  We identified and reviewed available literature on a
variety of topics including Gulf War illnesses, cancer epidemiology,
and other uses of federal and state medical information systems
(e.g., studies of cancer rates among Vietnam veterans potentially
exposed to Agent Orange).  We also interviewed officials from DOD,
VA, the National Cancer Institute, and the Medical Followup Agency of
the Institute of Medicine.  Through these interviews and materials
collected, we learned about the availability of data, their strengths
and limitations, and their applications for monitoring the incidence
of tumors and other illnesses.  We also discussed past and ongoing
research efforts to assess the magnitude and frequency Gulf War
illnesses with agency officials. 

An important limitation of our study is that we did not obtain the
databases and independently assess their reliability and validity. 
We did not, for example, assess data entry procedures to verify the
accuracy and completeness of reporting.  Furthermore, we did not
evaluate the effectiveness of database quality assurance practices. 

We conducted our review between July and December 1997 in accordance
with generally accepted government auditing standards. 

As agreed with your office, unless you publicly announce its contents
earlier, we plan no further distribution of this report until 30 days
from its issue date.  At that time, we will send copies of this
report to other interested congressional committees, the Secretaries
of Defense and Veterans Affairs, and other interested parties.  We
will also make copies available to others upon request. 

If you or your staff have any questions or would like additional
information, please contact me at (202) 512-3092.  Major contributors
to this report were John Oppenheim, Dan Engelberg, and Lï¿½ Xuï¿½n Hy. 

Sincerely yours,

Kwai-Cheung Chan
Director, Special Studies and Evaluations




(See figure in printed edition.)Appendix I
COMMENTS FROM THE DEPARTMENT OF
DEFENSE
============================================================== Letter 



(See figure in printed edition.)



(See figure in printed edition.)

*** End of document. ***