Prevalence of comorbid depression in schizophrenia: A meta-analysis of observational studies

Comorbid depressive symptoms (depression thereafter) often occur in schizophrenia and are associated with negative outcomes. This meta-analysis estimated the prevalence of comorbid depression and its associated factors in schizophrenia.

Both international (PubMed, EMBASE, PsycINFO, and Web of Science) and Chinese (WANFANG and CNKI) databases were systematically searched. Studies with data on the prevalence of comorbid depression in schizophrenia measured with the Calgary Depression Scale for Schizophrenia (CDSS) were included. Random-effects models were used in all analyses.

Fifty-three studies covering 9,879 patients were included. The pooled prevalence of comorbid depression was 28.6% (95%CI: 25.3%-32.2%). Subgroup analyses revealed that studies examining inpatients, being published in Chinese language, or those with lower CDSS cut-od values reported higher depression rates. Meta-regression analyses indicated that the rate of depression was positively associated with publication year, proportion of males, mean age, and severity of psychotic symptoms, and negatively associated with illness duration and study quality.

Comorbid depression is common in schizophrenia. Due to its negative impact on patients' quality of life and prognosis, regular screening and effective treatment for comorbid depression should be implemented in patients with schizophrenia.