High prevalence of underweight and undernutrition in Japanese inpatients with schizophrenia: a nationwide survey

OBJECTIVES: To clarify the prevalence of underweight and overweight/obesity, and laboratory data for nutritional status in Japanese outpatients and inpatients with schizophrenia. DESIGN: Cross-sectional study. SETTING: A questionnaire conducted in inpatient and outpatient facilities in Japan. PARTICIPANTS: The population of adult patients with schizophrenia in Japan (N=23 116). MAIN OUTCOME MEASURES: The prevalence of underweight and undernutrition in Japanese inpatients and outpatients with schizophrenia. RESULTS: We conducted a large-scale investigation of the prevalence of underweight and undernutrition in 520 outpatient facilities and 247 inpatient facilities belonging to the Japan Psychiatric Hospitals Association between January 2012 and July 2013. There were 7655 outpatients and 15 461 inpatients with schizophrenia. There was a significant difference in the distribution of three body mass index levels between outpatients and inpatients (p<0.001). The proportion of underweight inpatients with schizophrenia was significantly higher than that among outpatients (p<0.001). Age-specific analysis revealed that the proportion of underweight individuals aged ≥40 years was higher in inpatients than in outpatients and in the general Japanese population. The proportion of individuals with hypocholesterolaemia was significantly higher in inpatients with schizophrenia than in outpatients (p<0.001). There was a significant difference in the severity of underweight between outpatients and inpatients with schizophrenia; the proportion of severe underweight in inpatients was twofold higher than in outpatients. CONCLUSIONS: The prevalence of underweight and undernutrition in Japanese inpatients with schizophrenia was higher than in outpatients and the general population. Therefore, the physical risk of inpatients should be carefully considered in clinical practice.