Background Recent studies have suggested that opium use may increase mortality from cancer and cardiovascular diseases. However, no comprehensive study of opium use and mortality from respiratory diseases has been published. We aimed to study the association between opium use and mortality from respiratory disease using prospectively collected data.
Methods We used data from the Golestan Cohort Study, a prospective cohort study in northeastern Iran, with detailed, validated data on opium use and several other exposures. A total of 50 045 adults were enrolled from 2004 to 2008, and followed annually until June 2015, with a follow-up success rate of 99%. We used Cox proportional hazard regression models to evaluate the association between opium use and outcomes of interest.
Results During the follow-up period, 331 deaths from respiratory disease were reported (85 due to respiratory malignancies and 246 due to non-malignant aetiologies). Opium use was associated with an increased risk of death from any respiratory disease (adjusted HR 95% CI 3.13 (2.42 to 4.04)). The association was dose-dependent with a HR of 3.84 (2.61 to 5.67) for the highest quintile of cumulative opium use versus never use (Ptrend<0.001). The HRs (95% CI) for the associations between opium use and malignant and non-malignant causes of respiratory mortality were 1.96 (1.18 to 3.25) and 3.71 (2.76 to 4.96), respectively.
Conclusions Long-term opium use is associated with increased mortality from both malignant and non-malignant respiratory diseases.
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AR, RS, RM and FK contributed equally.
Correction notice This article has been corrected since it was published Online First. The spelling of the fourth author's name has been corrected.
Contributors Conception or design of the work: AR, RS, HK, RM, FK, PB, SMD, CCA, PDPP and PBr. The acquisition, analysisor interpretation of data for the work: AR, RS, HK, HP, AE, MK, AAS, AA, EJ, FI, SS, SG and FK. Drafting the manuscript for important intellectual content: AR, RS, FK, RM, FI, PB, CCA and SMD. Taking responsibility for the integrity of the work as a whole, from inception to published article: FK, RM, PB, SMD and CCA.
Funding The Golestan Cohort Study was supported by Tehran University of Medical Sciences (grant no: 81/15), Cancer Research UK (grant no: C20/A5860), Intramural Research Program of the US National Cancer Institute, National Institutes of Health and through various collaborative research agreements with the International Agency for Research on Cancer. The study has also received special support from the Social Security Organisation of Iran Golestan Branch.
Competing interests None declared.
Patient consent Obtained.
Ethics approval Ethical review boards of Digestive Disease Research Center of Tehran University of Medical Sciences, the International Agency for Research on Cancer and the US National Cancer Institute.
Provenance and peer review Not commissioned; externally peer reviewed.
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