Prevalence of underweight in patients with schizophrenia: A meta-analysis

Although the relationship between body mass index and all-cause mortality is U-shaped, underweight has received comparatively less attention than obesity. There is only limited evidence to date regarding underweight among patients with schizophrenia. This is the first meta-analysis to address the prevalence of underweight in these patients.

We conducted database searches (PubMed, PsycINFO) to identify studies examining underweight in patients with schizophrenia. In total, 17 studies (18 groups) with 45,474 patients were included; data were extracted independently by two authors. A meta-analysis was performed to calculate the pooled prevalence of underweight in patients.

The pooled prevalence of underweight was 6.2% (95% CI=4.5-8.6) for the 18 groups, which included 45,474 patients with schizophrenia. The heterogeneity was I²=98.9% (95% Cl=98.7-99.1%). Four studies with 4 groups, consisting of 30,014 individuals, focused on Japanese inpatients with schizophrenia. The pooled prevalence of underweight among inpatients in these 4 groups was 17.6% (95% CI=15.5-20.0). Fourteen studies were conducted with non-Japanese inpatients and included 14 groups of 15,460 patients with schizophrenia. The pooled prevalence of underweight in non-Japanese inpatients was 4.6% (95% CI=3.9-5.4). The proportion of underweight in the 18 groups significantly varied between Japanese inpatients and other patients.

The results indicated that Japanese inpatients with schizophrenia have a high proportion of underweight. Future research should focus on evaluating interventions that target underweight.