The prevalence and independent influencing factors of obesity and underweight in patients with schizophrenia: a multicentre cross-sectional study

Background: Few studies have investigated the weight of patients with schizophrenia in China. Objective: The aim of this study was to analyse the prevalence, clinical characteristics and influencing factors of obesity and underweight in patients with chronic schizophrenia in China. Methods: A total of 325 patients with schizophrenia and 172 sex- and age-matched healthy controls from the community were recruited. Socio-demographic data and laboratory measurements were collected for all subjects. Using the Positive and Negative Syndrome Scale (PANSS), we evaluated the psychiatric symptoms of patients with schizophrenia. According to the body mass index (BMI) criteria in China, BMI ≥ 28 kg/m² indicates obesity, and BMI < 18.5 kg/m² indicates underweight. Results: Of the patients with schizophrenia, 16.3% were obese, and 6.8% were underweight; 11.0% of the healthy controls were obese, and 3.5% were underweight. There was no difference between the two groups in the prevalence of obesity and underweight. After controlling for relevant variables, the obesity rate remained non significant, but the underweight rate appeared to be different. The multinomial regression analysis revealed that among the patients with schizophrenia, female sex, triglyceride level and LDL level were independent risk factors for obesity and that HDL level was an independent protective factor against obesity. In contrast, male sex and HDL level were independent risk factors for underweight. Conclusion: We found that the patients with schizophrenia had an increased rate of underweight and some factors related to weight. Level of evidence: Level V, descriptive study.