Bayesian spatial analysis of age differences and geographical variations in illicit-drug-related mortality in the Islamic Republic of Iran

Background: Drug use disorders are significant social and public health concerns in the Islamic Republic of Iran; however, little is known about drug-related mortality. Aims: We quantified the spatial and age distribution of direct illicit-drug-related mortality in the Islamic Republic of Iran, and inform harm reduction policies and interventions. Methods: We modelled and mapped registered illicit-drug-related deaths from March 2016 to March 2017. Data were obtained from the Iranian Forensic Medicine Organization. Besag–York–Mollie models were fitted using Bayesian spatial analysis to estimate the relative risk of illicit-drug-related mortality across different provinces and age groups. Results: There were 2203 registered illicit-drug-related deaths during the study period, 1289 (58.5%) occurred in people aged 20–39 years and among men (n = 2013; 91.4%). The overall relative risk (95% credible interval) of illicit-drug-related mortality in the provinces of Hamadan (3.37; 2.88–3.91), Kermanshah (1.90; 1.55–2.28), Tehran (1.80; 1.67–1.94), Lorestan (1.71; 1.37–2.09), Isfahan (1.40; 1.21–1.60), and Razavi Khorasan (1.18; 1.04–1.33) was significantly higher than in the rest of the country. Conclusion: We found evidence of age differences and spatial variations in illicit-drug-related mortality across different provinces in the Islamic Republic of Iran. Our findings highlight the urgent need to revisit existing drug use treatment and harm reduction policies and ensure that overdose prevention programmes are adequately available for different age groups and settings.