Estimating opium use prevalence at the national and provincial levels in Iran: a modelling study

Opium consumption was recently classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC). With Iran having the highest global prevalence of opium consumption, understanding the national and provincial prevalence of opium use is critical for cancer control efforts. This study integrated multiple data sources to estimate the prevalence of opium use across Iran. Using population-based cohorts and case-control studies we calculated opium use prevalence for 17 provinces of Iran. A regression model was then developed to explain geographical variation in opium use prevalence, incorporating demographic, socioeconomic, and opium-related national enforcement variables. The model was trained and validated using leave-one-out cross-validation for the 17 provinces with individual-level data, and was subsequently used to predict prevalence in the 14 remaining provinces lacking individual-level data. The age-standardized predicted prevalence of opium use among Iranian adults aged > 30 years was estimated at 5.93% (95% CI 2.76–8.20%), with a significant difference between men [10.40% (95% CI 4.69–14.30%)], and women [1.46% (95% CI 0.83–2.09%)]. Older age, lower socioeconomic status, unemployment, and higher quantities of seized opium were associated with higher opium use prevalence at provincial levels (all P-values < 0.05). Significant geographical variations in opium use prevalence were observed, with the highest rates estimated for the eastern provinces bordering Afghanistan, the world’s largest producer of opium, and the lowest rates in the northwestern provinces. The highest rates were calculated for Sistan and Baluchestan (15.00%), Golestan (13.43%), and Qom (13.07%), while the lowest were in Markazi (1.30%), Ilam (1.30%), and Zanjan (1.32%). Although the overall prevalence differed substantially between men and women, the geographic distribution patterns were similar for both. Opium consumption is highly prevalent among Iranian men and in populations residing in the eastern and southeastern provinces. Targeted public health interventions are urgently needed to reduce opium use, particularly in high-risk regions. These efforts should be integrated into national cancer control programs to effectively address the associated health burden.