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Linda A. McCauley, Sandy Joos, Michael R. Lasarev,
Daniel Storzbach, Dennis N. Bourdette and other members of PEHRC Portland
Environmental Hazards Research Center (PEHRC)
Most published reports of health symptoms among Persian
Gulf War (PGW) veterans are based on self-reports. The presence or unexplained
nature of self-reported symptoms has rarely been confirmed with clinical
evaluation. The purpose of this investigation was to assess the predictive
value of questionnaire data on self-reported health symptoms and to report
the degree of misclassification of health status as determined by clinical
evaluation.
The sample for this study was obtained from an ongoing population-based
case-control study of unexplained illnesses in PGW veterans. A random
sample of 1448 PGW veterans who listed Oregon or Washington as their home
state-of-record at the time of deployment was surveyed by questionnaire
for the presence of cognitive, fatigue, gastrointestinal, muscle/joint
and skin problems. The mail survey was followed by clinical examinations
assessing the presence and unexplained nature of health symptoms. Findings
from the first 228 subjects who completed clinical examinations indicate
significant differences between self-reported symptoms and those confirmed
at the time of clinical exam. The positive predictive value of self-report
by questionnaire varies across the symptom groups. While in 77% of subjects,
self-reported unexplained fatigue was confirmed by clinical exam, self-reported
gastrointestinal symptoms were confirmed by clinical exam in only 20%
of subjects. Differences in self-reported and clinically confirmed symptoms
were due to finding a clinical diagnosis for the symptom, resolution of
symptom(s) between time of questionnaire and clinical exam, and inadvertent
endorsement of the symptom on the questionnaire. Our findings suggest
that inappropriate conclusions may be drawn about effects of exposures
on health status from data based solely on self-report.
"Keywords:" Bias (epidemiology) Cross-sectional
studies Health histories
This work was supported by a grant from the Department of
Veterans Affairs to the PEHRC, a joint project of the Portland Veterans
Affairs Medical Center and the Center for Research on Occupational and
Environmental Toxicology, Oregon Health Sciences University. |
