AbstractAimsTens of millions of people worldwide use opiates but little is known about their potential role in causing cardiovascular diseases. We aimed to study the association of long-term opiate use with cardiovascular mortality and whether this association is independent of the known risk factors.Methods and resultsIn the population-based Golestan Cohort Study—50 045 Iranian participants, 40–75 years, 58% women—we used Cox regression to estimate hazard ratios and 95% confidence intervals (HRs, 95% CIs) for the association of opiate use (at least once a week for a period of 6 months) with cardiovascular mortality, adjusting for potential confounders—i.e. age, sex, education, wealth, residential place, marital status, ethnicity, and tobacco and alcohol use. To show independent association, the models were further adjusted for hypertension, diabetes, waist and hip circumferences, physical activity, fruit/vegetable intake, aspirin and statin use, and history of cardiovascular diseases and cancers. In total, 8487 participants (72.2% men) were opiate users for a median (IQR) of 10 (4–20) years. During 548 940 person-years—median of 11.3 years, >99% success follow-up—3079 cardiovascular deaths occurred, with substantially higher rates in opiate users than non-users (1005 vs. 478 deaths/100 000 person-years). Opiate use was associated with increased cardiovascular mortality, with adjusted HR (95% CI) of 1.63 (1.49–1.79). Overall 10.9% of cardiovascular deaths were attributable to opiate use. The association was independent of the traditional cardiovascular risk factors.ConclusionLong-term opiate use was associated with an increased cardiovascular mortality independent of the traditional risk factors. Further research, particularly on mechanisms of action, is recommended.