Using general population data to project idiopathic physical symptoms in the U.S. Army

Many personnel deployed to the 1991 Persian Gulf War complained of symptoms that sometimes remained unexplained after comprehensive clinical examinations. We used existing population-based data from the Epidemiologic Catchment Area survey to estimate the expected incidence, prevalence, resolution, and mortality for multiple idiopathic physical symptoms (MIPS) among Army active duty personnel. Multinomial logistic regression was used to model the relationship between sociodemographic characteristics and the distribution of MIPS in U.S. workers. We used logit coefficients and known sociodemographic characteristics of U.S. Army active duty personnel to predict MIPS status in the Army. High, medium, and low estimates of MIPS incidence, prevalence, resolution, and MIPS-related mortality were obtained by altering logit intercepts. Among workers, the estimated MIPS prevalence and annual incidence, resolution, and mortality were 4.62%, 2.11%, 63.85%, and 0.26%, respectively. In contrast, the same predicted rates among Army active duty personnel were 3.89%, 1.64%, 71.33%, and 0.15%.