Introduction
Major depressive disorder (MDD) plays a key role in the prognosis of schizophrenia and increases suicidal tendencies while hampering the quality of life.
Objective
To determine the prevalence of schizophrenia-MDD in stabilized schizophrenia real-world outpatients and to evaluate the associated factors dictating the schizophrenia-MDD prevalence.
Study Design
A Systematic Review and Meta-Analysis
Methods
Medline, Web of Science, PsycINFO, and Google Scholar databases were searched & 18 eligible studies including 6149 stabilized schizophrenia patients published until January 18, 2020 were included in the study. Amongst which, one study had poor quality (quality score = 13) and seven studies had high quality (quality score ≥ 25).
Results
- The pooled estimate of the prevalence of schizophrenia-MDD was 32.6% (95% CI: 27.9–37.6).
- A notable heterogeneity between studies was observed. (I2 = 92.587, p < .001)
- The prevalence ranged from 16.3% to 69.0%. While one of the two highest prevalence’s reported in a study included a homeless population in France (50.5%), the other was the only study conducted using the PHQ questionnaire (69.0%).
- The results of the leave-1-out sensitivity analyses demonstrate that no single study had an unreasonable effect on the pooled estimate of the prevalence of schizophrenia-MDD.
- The prevalence of schizophrenia-MDD was found to be higher in studies published in or after 2015 (39% vs 27.3%, p = .031).
- A higher prevalence was observed in studies using self-reported questionnaires (46.9% [3 studies]) than in studies using clinician rated-questionnaires (CDSS 30.1% [10 studies] and studies using structured clinical interviews (16.4% [2 studies], p < .001).
- Patients having substance use disorders had higher prevalence (38.2% vs 27.5%, p = .020)
- A higher risk was observed in patients with chronic somatic illnesses (40.8% vs 26.6%, p < .001).
Conclusion
Schizophrenia-MDD was identified in about one-third of schizophrenia stabilized patients indicating high prevalence of MDD in schizophrenia patients. Older and less-educated patients, individuals indulging in substance abuse and those suffering from chronic somatic illness should be targeted for screening, treatment and prevention.