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

Abstract

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.

Keywords: Age; Mental health multimorbidity; Race/ethnicity; Sex; Somatic multimorbidity.

Figure 1.

Prevalence (per 100 population) of combinations of 2 or more of the 19 chronic conditions (general multimorbidity) by sex (panel A) and by race/ethnicity (panel B). Prevalence of somatic–mental multimorbidity (SMM) by sex (panel C) and by race/ethnicity (panel D).

Figure 2.

Heat maps of the prevalence of somatic–mental multimorbidity dyads (number of dyads per 100 population) stratified by age and sex. The value in each square is the percentage of co-occurrence in the population (prevalence of a given dyad). The 5 mental health conditions are presented in rows, and the 14 somatic health conditions are presented in columns; the color scale is shown on the right. The definitions of acronyms or abbreviations are: ANX = anxiety disorders; ARR = cardiac arrhythmias; ART = arthritis; AST = asthma; CAD = coronary artery disease; CAN = cancer; CHF = congestive heart failure; COPD = chronic obstructive pulmonary disease; CKD = chronic kidney disease; DEM = dementia and cognitive disorders; DEP = depressive disorders; DIA = diabetes; HEP = hepatitis; HTN = hypertension; LIP = hyperlipidemia; OST = osteoporosis; STR = stroke; SUB = substance abuse disorders; SZO = schizophrenia.

Figure 3.

Heat maps of a risk ratio obtained by dividing the observed frequency of each pair of conditions by the frequency expected assuming independent probabilities stratified by age and sex (observed-to-expected ratios; OERs). We only displayed OERs for dyads that occurred in five or more persons and that reached statistical significance. The hotter colors (orange) correspond to higher frequencies of co-occurrence than expected, whereas the cooler colors (purple) correspond to lower frequencies than expected. The 5 mental health conditions are presented in rows, and the 14 somatic health conditions are presented in columns; the color scale is shown on the right. The definitions of acronyms or abbreviations are: ANX = anxiety disorders; ARR = cardiac arrhythmias; ART = arthritis; AST = asthma; CAD = coronary artery disease; CAN = cancer; CHF = congestive heart failure; COPD = chronic obstructive pulmonary disease; CKD = chronic kidney disease; DEM = dementia and cognitive disorders; DEP = depressive disorders; DIA = diabetes; HEP = hepatitis; HTN= hypertension; LIP = hyperlipidemia; OST = osteoporosis; STR = stroke; SUB = substance abuse disorders; SZO = schizophrenia. N < 5 = the dyad was present in fewer than five patients. ns = the OER was not statistically significant.