Affordability Analysis of Selected Medicines in Iran: A National Cross-sectional Survey Using World Health Organization Out-of-Pocket Methodology.

Background: Increased costs of prescription drugs impose tremendous economic burdens on patients globally, which usually result in low drug adherence and poor health outcomes. In Iran, out-of-pocket (OOP) expenditures are severe, particularly among vulnerable groups such as the elderly. This analysis reviews OOP expenditures of 51 medications in Iran to provide useful insights regarding healthcare policy. Objectives: To analyze OOP payments for medications in Iran during a seven-year period, revealing trends, financial needs, and policy requirements that increase financial protection and drug access. Methods: We included 51 medicines, meeting the WHO/HAI minimum sample size requirement for reliability (n = 50), consisting of the universal core list (n = 14) and a supplementary list based on local disease prevalence (n = 37). Following RECORD guidelines for observational studies, data were sourced from the two largest national health insurance funds [Social Security Organization (SSO), Iran Health Insurance Organization (IHIO)], covering the majority of the Iranian population, and pharmacy records from 2016 to 2022. OOP costs, insurance coverage, and affordability were analyzed using impoverishing health expenditure (IHE) and catastrophic health expenditure (CHE) metrics. To control for economic confounders, costs were adjusted using purchasing power parity (PPP). Joinpoint regression assessed annual OOP changes, with significance set at P-value < 0.05. Results: Over the seven-year period, PPP-OOP payments showed a non-significant decreasing trend [average annual percent change (AAPC): -1.2% for SSO; -1.38% for IHIO]. Despite this, OOP expenditure remained high, averaging approximately 40% of total medication costs. Significant heterogeneity was observed; for instance, Spironolactone saw the highest cost increase (AAPC +8.29%), while Insulin Glargine showed the largest decrease (AAPC -12.59%). High OOP payments were observed for medications like dexamethasone and chlorpromazine, while insulin and clozapine also carried high costs under insurance. The variability in OOP expenses across medicines highlights differences in pricing and insurance policies. Catastrophic expenses were prominent for certain medications, such as enoxaparin, especially at higher expenditure thresholds based on the 40% capacity-to-pay metric. Limitations included the use of administrative claims data subject to potential operational errors and the restriction of the sample to 51 medicines, which may limit generalizability to the broader pharmaceutical market. Conclusions: This research reveals high OOP spending for Iranian patients, with considerable drug-specific heterogeneity. The implications suggest that policy action in terms of price reform and wider insurance coverage is needed to minimize financial burden and ensure access to medicines. Further studies are required to determine the impact of high OOP spending on patient adherence and to inform specific health policies in Iran and beyond.