Prevalence of Combined Somatic and Mental Health Multimorbidity: Patterns by Age, Sex, and Race/Ethnicity

Background: The coexistence of chronic mental health conditions with somatic conditions (somatic-mental multimorbidity, or SMM) is common and has been associated with greater symptom burden and functional impairment, higher costs, and excess mortality. However, most existing literature focused on the co-occurrence of an index mental health condition with specific additional conditions. By contrast, we studied the prevalence and patterns of SMM more broadly considering 19 selected conditions, and we focused on differences by age, sex, and race/ethnicity. Methods: The Rochester Epidemiology Project (REP) records-linkage system was used to identify all residents of Olmsted County, MN, on April 1, 2010. We identified individuals with each of 19 common chronic conditions, including 5 mental health conditions, using the International Classification of Diseases, ninth revision (ICD-9) codes received from any health care provider between April 1, 2005 and March 31, 2010. Results: Among the 138,858 residents of the county, 52.4% were women, and 7.9% had SMM. SMM increased steeply with older age, was 1.7 times more common in women, and was lower in Asians compared with whites. Of the 10,903 persons with SMM, 7,739 (71.0%) were younger than 65 years. Depressive and anxiety disorders were the most common conditions involved in SMM. The dyads that were observed more frequently or less frequently than expected by chance varied in composition by age and sex. Conclusions: SMM that reaches medical attention is highly prevalent across all age groups, is more frequent in women, is less frequent in Asians, and encompasses a wide range of conditions.