Herbicide Exposure, Vietnam Service, and Hypertension Risk in Army Chemical Corps Veterans :

Since the introduction of Cohen's kappa as a chance-adjusted measure of agreement between two observers, several "paradoxes" in its interpretation have been pointed out. The difficulties occur because kappa not only measures agreement but is also affected in complex ways by the presence of bias between observers and by the distributions of data across the categories that are used ("prevalence"). In this paper, new indices that provide independent measures of bias and prevalence, as well as of observed agreement, are defined and a simple formula is derived that expresses kappa in terms of these three indices. When comparisons are made between agreement studies it can be misleading to report kappa values alone, and it is recommended that researchers also include quantitative indicators of bias and prevalence.

This study assessed agreement between self- and medical record report of medical conditions in an elderly population. Medical charts of 120 participants in a screening program were abstracted, and the questionnaire report of eight major conditions was compared with the medical record. There was substantial or moderate agreement between self-report and medical record report for each condition, although strength of agreement varied by condition. Self-report by elderly individuals compares favorably with medical record report of medical conditions.

Research suggests that posttraumatic stress disorder (PTSD) may be associated with later medical morbidity. To assess this, we examined all-cause and cause-specific mortality among a national random sample of U.S. Army veterans with and without PTSD after military service. We used Cox proportional hazards regressions to examine the causes of death among 15,288 male U.S. Army veterans 16 years after completion of a telephone survey, approximately 30 years after their military service. These men were included in a national random sample of veterans from the Vietnam War Era. Our analyses adjusted for race, Army volunteer status, Army entry age, Army discharge status, Army illicit drug abuse, intelligence, age, and, additionally -- for cancer mortality -- pack-years of cigarette smoking. Our findings indicated that adjusted postwar mortality for all-cause, cardiovascular, cancer, and external causes of death (including motor vehicle accidents, accidental poisonings, suicides, homicides, injuries of undetermined intent) was associated with PTSD among Vietnam Theater veterans (N = 7,924), with hazards ratios (HRs) of 2.2 (p < 0.001), 1.7 (p = 0.034), 1.9 (p = 0.018), and 2.3 (p = 0.001), respectively. For Vietnam Era veterans with no Vietnam service (N = 7,364), PTSD was associated with all-cause mortality (HR = 2.0, p = 0.001). PTSD-positive era veterans also appeared to have an increase in external-cause mortality as well (HR = 2.2, p = 0.073). Our study suggests that Vietnam veterans with PTSD may be at increased risk of death from multiple causes. The reasons for this increased mortality are unclear but may be related to biological, psychological, or behavioral factors associated with PTSD and warrant further investigation.