A novel population-based health index for mental disorder.

INTRODUCTION A novel population-based health index was identified, in addition to calculation of the rates of psychiatric disorder in a random sample from a large urban center. METHODS With use of the regional population as a sampling frame, 685,684 individuals (45.8% male) were selected randomly, with physician billing visit and cost data from 1994 to 2009 grouped on the basis of the presence or absence of a psychiatric disorder. The prevalence of psychiatric disorder was described and the groups were further analyzed in terms of somatic and biomedical disorders with the profile of depression highlighted. RESULTS In the sample (45.8% male), the annual prevalence of psychiatric disorder from 1994 to 2009 was found to increase in 3 age strata (children, 5.3%; adults, 4.4%; and geriatric subjects, 6.2%). Depressive disorders as a group provided an example of the population profile. The cumulative rate of psychiatric disorder was 53% over 16 fiscal years. In comparison with the group without psychiatric disorder, the median cost of physical (biomedical/somatic) disorders was 2.9 times higher for the group with any International Classification of Diseases psychiatric disorder. DISCUSSION The arithmetic ratio of median somatic and biomedical health costs, comparing groups with and without psychiatric disorders, was presented as a novel population health index that holds the potential to directly measure the impact of promotion and prevention programs associated with psychiatric disorders.