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COVARIATES, CONFOUNDERS, AND CONSISTENCY: CHARACTERIZING THE VIETNAM VETERAN FOR 27 EPIDEMIOLOGIC STUDIES ⢠A survey of a population of womenâboth veterans and civiliansâwho were stationed in Vietnam during the conflict and on whom few data are available. FOLLOW-UP OF THE AMERICAN LEGION SURVEY Enduring Effects of Vietnam Service The researchers recovered the original data files and identified the earlier cohort of 12,748 men who were randomly sampled from the American Legion membership for a 1984 survey (the Wave 1 survey). The American Legion membership department was able to trace about 60% of them from current membership roles. An additional 12% were then located by attending Legion state conventions, networking with attendees, and circulating lists of âmissingâ Legionnaires to individual legion posts (organizational units). Some remaining veterans were found through online searches and use of a commercial credit-rating service that maintains an extensive name and address database. Of the 72% found, a follow-up determined that some were deceased and a small number were not eligible for participation because their service did not meet the study requirements. In total, 63% of the original cohort was sent questionnaires. A survey nearly identical with that used in 1984 was reviewed and slightly amended after discussions with VA and American Legion officials, subjected to institutional review board approval at Columbia University, and mailed to nearly 9,000 Legionnaires in 1998 (the Wave 2 survey). Investigation of the data on respondent characteristics and the response rate yielded some interesting results that are potentially important for future epidemiologic studies. Those with the highest posttraumatic stress disorder (PTSD) scores and those in the poorest health were much more likely to be lost to followup. It has been found that PTSD is highly correlated with combat and combat with Agent Orange exposure scores, so special care must be taken in the design of study populations and the execution of epidemiologic studies to ensure that one does not miss precisely the groups one is most interested in studying. Papers addressing the survey methods and results in greater detail are listed in Appendix A.
