information on the variability of depressive symptoms among POWs. Even the so-called lifetime prevalence data, based on the results of a single exam, could be refined and expanded by supplementing exam findings with earlier data from questionnaires and records to obtain a more complete, accurate measure of lifetime prevalence.
Closely related to these kinds of analyses are longitudinal studies that would link data collected earlier to subsequent outcomes. One example is the use of 1984–1985 data on depressive symptoms, together with demographic data on such factors as age and education, to predict PTSD rates in the current examination. Including some of the 1967 data from the Cornell Medical Index as well as even earlier hospitalization data (although cumulative response rates could be a problem) would permit an analysis linking five decades worth of information—a unique opportunity to explicate the processes by which such diseases progress.
Of course, a study such as this one always suggests new data that might be collected, but the disappointingly low response rates for this exam make new data collection even more important. New studies focused on a narrower clinical area and smaller and perhaps less geographically dispersed groups should have a better chance of achieving high response rates—the nerve conduction studies done by Hong at the Livermore VA Medical Center offer an example. If such efforts were to be mounted using a sample of the current respondents from the MFUA survey, any new clinical findings could be related to the examination data that have already been collected as well as to risk factor data in earlier questionnaires and records. The conditions in Table 6.7 would be obvious candidates for small-scale clinical studies, but others could also be profitably studied. The detailed diagnostic tabulations in Appendix C, which are described in Chapter 8, are provided as reference material to guide such investigations.
Finally, it has been approximately 15 years since the last mortality follow-up was completed. There is considerable speculation about current death rates among POWs but no comprehensive data. Although conditions like peripheral neuropathy and osteoarthritis can only be studied reasonably as morbid conditions, other conditions can be better investigated by using mortality data. An important point in favor of mortality studies—especially given the low response rates confronted in this study—is the completeness of death reporting, customarily 90% or better. The analyses of Chapter 6 suggest that simple comparisons of POWs and controls may not be as powerful a mechanism to identify associations with military captivity as are explicit analyses of the associations between health outcomes and prison camp factors. To date, the mortality analyses of the MFUA cohort have not attempted to associate mortality rates directly with prison camp factors. Such analyses could be undertaken and, with an additional 15–20 years of mortality data, might uncover further unsuspected links between the POW experience and subsequent medical conditions.