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; I²=47%). The pooled OR of opium use and CVD in-hospital mortality was not statistically significant (OR: 1.44, 95% CI = 0.88-2.36, I²  = 51%). In the stratified analysis, in the patients who had undergone heart surgery, the average of ejection fraction (EF) in the opium users was significantly lower than those not using opium (mean differences: -3.06, CI 95% = -4.40 to -1.71, I² = 60%) but in the patients with acute myocardial infarction undergoing angiography, the average EF was not significantly different in the opium users compared to non-users (mean difference: 0.30, CI: -0. 55 to 1.15). The results of this meta-analysis revealed that opium might be a risk factor for CAD and EF but not in-hospital mortality.