National, Subnational, and Risk-Attributed Burden of Chronic Respiratory Diseases in Iran (1990-2021): A Longitudinal Clustering Analysis of Global Burden of Disease 2021 Data.

Background and Aims: Policymakers require accurate and localized data on the burden of chronic respiratory diseases (CRDs) to allocate resources and design targeted interventions. Our objective was to explore longitudinal patterns in CRD metrics across Iranian provinces over three decades, leveraging recent subnational estimates from Global Burden of Disease (GBD) 2021 to derive actionable public health insights. Methods: We used longitudinal K-means clustering (KmL) to identify provincial-level trends in age-standardized rates (ASRs) of mortality (ASMR), prevalence (ASPR), and incidence (ASIR) attributable to CRDs, including asthma and COPD. Risk-attributed burden estimates were also examined for major environmental and occupational exposures. Results: CRD-related ASMR, ASPR, and ASIR decreased nationally between 1990 and 2021. Sistan-Baluchestan and South Khorasan provinces showed the highest cluster profiles for ASIR and ASPR, while Kerman province alone formed the highest mortality (ASMR) cluster. Among modifiable exposures, tobacco use dominated male-attributed CRD burden, whereas air quality indicators, particularly particulate pollutants, were more prominent among females. Kerman also had the highest burden of CRD mortality due to occupational risks and air pollution. Conclusion: Geographical inequalities and distinct risk profiles underline the need for region-specific prevention strategies. National-level interventions to reduce exposure to modifiable risk factors, particularly smoking and air pollution, are essential to further reduce the burden of CRDs in Iran.