Abstract
BACKGROUND: This meta-analysis aimed to investigate serum and plasma malondialdehyde (MDA) levels in patients with obsessive-compulsive disorder (OCD) in comparison to healthy controls. METHODS: Following the PRISMA protocol, we searched for the relevant studies through the databases of Scopus, PubMed, Google Scholar, and web of science until September 2019 with no time restriction. Overall, nine studies were included in the current meta-analysis. Data were pooled using a random-effects model; in addition, standard mean difference (SMD) and/or weight mean difference (WMD) was calculated. Cochran's Q test and I-square (I(2)) statistics were used to evaluate between-study heterogeneity. The Newcastle-Ottawa scale (NOS) was used to evaluate the quality of the included studies. Statistical analyses were done using the STATA version 14. RESULTS: Our systematic review included nine case-control studies (including 367 cases and 337 controls). Pooling findings from these studies showed a significantly higher MDA level in OCD patient compared to control groups (SMD = 1.62; 95% CI [0.53, 2.72]; I(2) = 96.9%; Pheterogeneity (Ph) < 0.001). This finding remained unchanged among studies which reported MDA in the same unit (WMD = 1.93; 95% CI [0.27, 3.59]; I(2) = 99.2%; Ph < 0.001). Subgroup analysis by the study location and sample size revealed findings that were also significant. CONCLUSION: We found that MDA levels are higher in OCD patients than healthy controls. This finding highlights the importance of inflammatory responses in OCD patients that should be considered for future investigations. Further studies are recommended to expand current knowledge on this issue.