Body mass index among Japanese inpatients with schizophrenia

Many studies have emphasized the high frequency of obesity in schizophrenic patients. However, the characteristics of the Body Mass Index (BMI) distribution in Japanese schizophrenic patients remain unknown, and the aim of this study was to clarify these characteristics in a Japanese schizophrenic inpatient population.

The subjects were 273 inpatients (males: 141, females: 132) with schizophrenia. The patient BMI distribution was compared with normal control data obtained from the 2003 Japanese National Health and Nutrition Survey.

The mean patient BMI was 23.0 +/- 4.3, and the BMI showed a normal distribution. The proportion of patients who were obese, of normal weight and underweight was 30.8%, 53.1%, and 16.1%, respectively. No statistical evidence of a higher frequency of obesity was found in male patients, compared to normal controls, but a higher frequency of underweight patients and a lower frequency of normal-weight patients were apparent in most decades of age. In female schizophrenia patients, a higher prevalence of obesity occurred in patients aged 50-59 years old, compared to controls. A higher rate of underweight elderly patients and a lower rate of normal-weight patients aged 40 to more than 70 years old were also apparent.

The results suggest that not only obesity but also weight problems related to an underweight condition occur more frequently in Japanese schizophrenic inpatients than in normal controls. The deviation of the BMI distribution in Japanese schizophrenic inpatients may have a relationship with higher mortality and sudden death in schizophrenia.