Suicide is the leading cause of unnatural death among people with a diagnosis of schizophrenia. Alcohol use is a prevalent comorbid feature of schizophrenia and a modifiable risk factor for suicide. We conducted a prospectively registered (PROSPERO, CRD42022358214) systematic review and meta-analysis to quantify the relationship between alcohol use and suicide-related outcomes in schizophrenia.We searched Medline, Embase, and PsycINFO for cross-sectional, case-control and longitudinal studies using exhaustive terms from database inception to December 2022 inclusive. Computation of odds ratios (ORs) and hazard ratios (HRs) were performed using a random-effects model with DerSimonian-Laird estimation. We also evaluated publication bias, study quality, and performed subgroup analysis and meta-regression. Fifty studies, comprising 65 samples, met eligibility criteria. Overall, alcohol use was associated with suicide (OR 1.38, 95% CI 1.21-1.58; HR = 1.32, 95% CI 1.00-1.74), attempted suicide (OR 1.69, 95% CI 1.45-1.98), and suicidal ideation (OR 1.69, 95% CI 1.22-2.34). While there was no evidence of publication bias, between-sample heterogeneity was moderate in analyses of attempted suicide (I2 = 39.6%, p = 0.01) and suicidal ideation (I2 = 56.0%, p = 0.01). Summary effects were significant in all subgroups except for longitudinal studies of attempted suicide (OR 1.60, 95% CI 0.86-3.00) and studies of suicidal ideation using gender combined samples (OR 1.63, 95% CI 0.99-2.67). Alcohol use is significantly associated with suicide-related outcomes in schizophrenia. Clinicians should routinely inquire about alcohol use in mental health services to focus preventative treatment efforts.
Keywords: alcohol; attempted suicide; schizophrenia; suicidal ideation; suicide.