Predictors of physical functioning among adults with severe mental illness

Living conditions and treatment-related factors contribute to high rates of comorbid medical illness among adults with severe mental illness and undermine their physical well-being. This study examined physical functioning scores for this population and compared them with national norms.

A total of 309 residential care clients completed interviews. Diagnostic and sociodemographic variables were examined for significant associations with physical functioning, which was assessed with the Medical Outcomes Health Survey Short Form 36 (SF-36), and selected variables were entered into a hierarchical multiple regression analyses. Cross-sectional comparisons examined differences in scores between ten-year age groups in this sample and in the national data for men and women.

In the final regression model, male gender, younger age, having earned income in the past six months, having less lifetime smoking, and having an admission diagnosis other than depression or schizophrenia spectrum disorders predicted better physical functioning. Functioning scores for the sample deviated from the national normed scores. Differences in functioning increased with each ten-year increment in age; study participants' functioning resembled that of cohorts ten to 20 years older.

Determinants of physical functioning in this sample included well-known demographic predictors of health outcomes. The more striking finding was a deviation from normative data that began for study participants at the age of 25 years, indicating an early onset of limitations. The consistent trend of poorer functioning with each successive age group raises questions about the pace of physical decline among adults with mental illness that may be addressed in longitudinal studies.