Predictors of Body Mass Index in Individuals with Serious Mental Illness Receiving Integrated Health Services

Background

Persons with serious mental illness (SMI) are disproportionately affected by largely preventable cardiometabolic conditions and experience heightened mortality and morbidity.  Community mental health centers have aimed to reduce longstanding health disparities by co-locating primary healthcare, prevention, and wellness services. The extant research demonstrates a consistently strong association between elevated risk of obesity and certain psychotropic medications used to treat thought disorders; however; however, this relationship has not been examined in clients receiving integrated primary and behavioral healthcare (PBHC) services. The current study addresses this gap by examining the relative influence of socio-demographic (gender, race, education and employment level), certain health (health indicators, self-assessed health, medication type and risk), health-risk (use of tobacco, alcohol, illicit drugs; personal history of diabetes, hypertension, heart disease), and psychosocial characteristics (social support, functioning, psychological distress) on measures of obesity in persons with SMI.

 Methodology

Researchers collected data from the health records of persons with MDD (N=449) receiving integrated PBHC services at one CMH center. A subsample of 177 cases was randomly generated and data measuring psychotropic medications were coded according to type and level of cardiometabolic risk. Mechanical health indicators included systolic and diastolic blood pressure (BP) and body mass index (BMI). Laboratory health indicators included measures of blood glucose, high-density-lipoproteins (HDL), low-density-lipoproteins (LDL), triglycerides (TRI), and lipid total. Health status was assessed with one general self-rated health item. Social support was measured with the 4-item Perception of Social Connectedness (PSC) subscale of the Mental Health Statistics Improvement Program (MHSIP). Psychological distress was assessed with the K6, and daily functioning was measured with the 8-item Perception of Functioning (PF) subscale of the MHSIP.  First, bivariate analyses were conducted to examine zero-order correlations between major variables of interest. Ordinary least squares (OLS) regression was employed using a forced entry method to examine the predictive ability of significant correlates (at r ≥.20) on BMI.

 Results

The average BMI score was 33.0 (SD=9.51), with 362 (80.4%) showing at-risk scores. The majority of participants was prescribed a regimen of antipsychotic and antidepressant medications (32.8%), with smaller proportions prescribed antidepressants (26.6%) or antipsychotics (14.7%). Based on the results of bivariate analyses, the following significant correlates of BMI were included in the OLS regression model: gender (r=24), blood glucose (r=27), history of hypertension (r=.21), tobacco use (r=.-21), and systolic (r=.28) and diastolic BP (r=.33). The inclusion of all predictor variables in the equation explained approximately 17% of the variance in BMI (R=.41, R² =.171,R²_adj=.145). The model was significant, at F(5,160) = 6.61,p<.001. Among correlates, female gender (beta=.18, p<.05), diastolic BP (beta=.23, p<.01), and (beta= .162, p<.05) were significant predictors of BMI.

 Implications

Psychotropic medication type did not emerge as a correlate of BMI in the current study. Results indicate heightened risk for women, suggesting the presence of additional, gender-based disparities among CMH clients in integrated PBHC programs. Findings underscore the importance of targeting individuals with SMI who show multiple risks factors for obesity.