Background: There are differences of opinion about the beneficial or detrimental effects of opium consumption on cardiovascular diseases (CVDs). So, we aimed to study the association between opium use and CVDs.

Methods: We used data obtained from the Rafsanjan Cohort Study (RCS), as a part of the prospective epidemiological research studies in IrAN (PERSIAN), with detailed, validated data on opium consumption and some other exposures. A total of 10,000 adults were enrolled in the study. Logistic regression models were used to assess the possible relationships of opium consumption with the prevalence of ischemic heart diseases (IHD) and myocardial infarction (MI).

Results: In this study, 9990 participants in the baseline phase of the Rafsanjan adult cohort study were included according to their completed questionnaire. Among all participants, 870 and 296 individuals were found to suffer from IHD and MI, respectively. Opium consumption was found to be relatively high in the RCS participants, especially in men (men = 2150 and women = 228). Opium use was associated with a higher odds of IHD and MI, with the adjusted odds ratios (95% CI) of 1.51 (1.22-1.86) and 1.79 (1.31-2.45), respectively. Also, dose-response increases were observed with the highest odds ratios in the 4th quartile for MI and IHD (p-values for trend < 0.001). Increased odds were observed for the two main methods of opium consumption, i.e. oral and smoking, but oral administration had higher odds ratio. Conclusions: Opium consumption is associated with the increased odds of both IHD and MI diseases.