An univariate substudy examined the prevalence of STD in approximately 180 patients from the substudy II cohort who had completed a psychosocial stress interview in order to determine if elevated psychosocial stress was associated with STD. A second univariate substudy examined the effect of diabetes on the prevalence of STD. A third univariate substudy examined the effect of STD on the prevalence of arrhythmia.