Multiple idiopathic physical symptoms in the ECA study: competing-risks analysis of 1-year incidence,mortality, and resolution. Epidemiological Catchment Area

OBJECTIVE: Competing-risks analysis was used to determine the 1-year longitudinal outcomes, including mortality, associated with multiple idiopathic physical symptoms in a population sample. METHOD: The authors analyzed baseline and 1-year follow-up data from the population-based NIMH Epidemiological Catchment Area Study. Multinomial logit regression was used to examine the incidence of multiple idiopathic physical symptoms, resolution of such symptoms, and related mortality among individuals in the general population, with adjustment for demographic characteristics and the presence or absence at baseline of a lifetime diagnosis of major depression, dysthymia, anxiety disorder, and alcohol abuse. Multinomial logit modeling also accounts for the impact of competing outcomes, such as survey nonresponse. RESULTS: Most of the individuals with multiple idiopathic physical symptoms recovered over the ensuing year. The incidence of multiple idiopathic physical symptoms among those without such symptoms at baseline was 1.7%. The predicted mortality among individuals with multiple idiopathic physical symptoms at baseline was higher than for individuals not having such symptoms at baseline (0.28% versus 0.18%). The higher mortality rate among those with multiple idiopathic physical symptoms at baseline persisted after adjustment for covariates and competing outcomes. CONCLUSIONS: Outcomes associated with multiple idiopathic physical symptoms vary widely. Most individuals improve over time. However, the course for a few individuals is less benign than perhaps previously thought. Further research is needed to determine the mechanisms behind increases in mortality related to multiple idiopathic physical symptoms, the predictors of poor prognosis, and whether mortality remains elevated over longer periods of follow-up.