Opium use and cardiovascular diseases: a systematic review and meta-analysis.

The effects of opium on cardiovascular diseases (CVDs) have been extensively studied. However, there are few studies that summarize this research comprehensively; thus, this systematic review and meta-analysis is a collection of the newest information combined with previous findings to furthermore illuminate the effects of opium on CVDs. In this systematic review, all observational studies were systematically searched using the main international databases such as PubMed/Medline, Web of Sciences, and Scopus until October 2018. After the quality assessment of the articles, the fixed or random model meta-analysis was used to pool the results. I-square test was used to assess the heterogeneity of the studies. Overall, 41 studies were identified. Based on the random model, the pooled odds ratio (OR) (95% confidence interval (CI)) of opium use and coronary artery diseases (CAD) was estimated at 2.75 (95% CI = 2.04-3.75; I