Relationship between obsessive compulsive symptomatology and severity of psychotic symptoms in schizophrenia: Meta-analysis and meta-regression analysis

Background: Schizophrenia patients often show obsessive-compulsive symptoms (OCS) and obsessive-compulsive disorder (OCD) and their presence has been associated with poorer prognosis. However, the impact of OCS/OCD on psychotic severity remains unclear. The aim of this study is twofold: 1) to investigate the effect of OCS/OCD on the severity of positive, negative, and global psychotic symptoms of schizophrenia patients and 2) to analyze the effect of patient and study-related covariates on moderating this relationship.Methods: A systematic review and meta-analysis (SRMA) of studies comparing the severity of psychotic symptoms among schizophrenia patients with and without OCS/OCD was performed. Standardized mean difference (SMD) was calculated for positive, negative, and global psychotic symptoms. The difference of SMD (Diff SMD) was calculated to analyze the effect of covariates on study outcomes using meta-regression.Results: Sixty-seven studies involving 7740 patients were included. Patients with schizophrenia and OCS/OCD showed a slightly higher severity of positive (SMD = 0.17, p value = 0.0089) and global psychotic symptoms (SMD = 0.24, p value = 0.0104) than patients without OCS/OCD but no differences in negative symptoms were found between groups (SMD = 0.11, p value = 0.0367). Only one covariate "proportion of patients without antipsychotics (AP)" was found to modify the effect on psychotic severity (Diff SMD = -0.008, p value = 0.002).Conclusions: Comorbid OCS/OCD in schizophrenia has, at most, a minor impact on psychotic severity. Variability in this effect was considerable and was poorly explained by the covariates analyzed.