Predictive Utility of Body Mass Index for Metabolic Syndrome Among Patients with Schizophrenia in Japan

Background Reliable and easy screening for metabolic syndrome (MetS) is important for patients with schizophrenia. The aim of this study was to assess the predictive utility of body mass index (BMI) for MetS among patients with schizophrenia in Japan. Methods In total, 8468 patients (4705 males, 3763 females) with schizophrenia or schizoaffective disorders based on the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), or the International Classification of Diseases, tenth revision (ICD-10), were assessed for MetS using the criteria of the National Cholesterol Education Program Adult Treatment Panel III (ATP III-A). We applied a stratum-specific likelihood ratio (SSLR) analysis, which is independent of the prevalence of the target disease. Results The mean (± standard deviation) age of these patients was 57.4 ± 13.5 years. The prevalence of MetS was 20.4%. Among males, the SSLRs predicting MetS were 0.03 (95% CI 0.02-0.06), 0.54 (95% CI 0.48-0.60), 2.77 (95% CI 2.44-3.14) and 8.75 (95% CI 7.40-10.36) for BMI <20 kg/m2, 20 kg/m2 ≤ BMI < 25 kg/m2, 25 kg/m2≤ BMI < 28 kg/m2, and 28 kg/m2≤BMI, respectively. For females, the SSLRs predicting MetS were 0.08 (95% CI 0.05-0.12), 0.73 (95% CI 0.66-0.82), 2.50 (95% CI 2.16-2.90) and 4.83 (95% CI 4.12-5.67) for the same BMI categories, respectively. Conclusion The predictive utility of BMI is confirmed, and BMI has more predictive value in males than in females. Patients with a BMI of 28 kg/m2 or greater had a significantly higher SSLR than those with a BMI less than 28 kg/m2.