The impact of obesity on health care costs among persons with schizophrenia

Abstract

Background Obesity is the second leading cause of preventable death in the United States and is twice as common among individuals with schizophrenia as the general population. Methods Data from the Clinical Antipsychotic Trials of Intervention Effectiveness, a multisite trial of antipsychotic pharmacotherapy in 1460 patients with schizophrenia, were used to examine the relationships between body mass index (BMI) and medical costs. Results ANCOVA analyses found significant increases in both psychiatric and nonpsychiatric medication costs associated with increasing BMI and a significant, but smaller, difference in costs of outpatient medical–surgical service utilization: US$41 per month for morbidly obese patients compared to US$26 per month for patients of normal weight ( F=2.4, P=.04). In multivariable logistic regression analyses, morbid obesity was associated with significantly increased odds of any outpatient medical–surgical service costs. When compared to observations of BMI>35, BMI observations within the normal range (18.5–24.9) were half as likely to be associated with any outpatient medical–surgical costs (OR=0.53; 95% CI=0.45, 0.63). Conclusions In this large sample of persons with schizophrenia, obesity was associated with increased outpatient general medical service and medication costs even after controlling for demographic characteristics and medical comorbidity, but the absolute dollar amount was small.