Tabriz University of Medical Sciences Health Promotion Perspectives 2228-6497 16 3 2026 11 05 Urban Family Physician Program and Out-of-Pocket Health Expenditures in Iran: A Quasi-Experimental Interrupted Time Series and Difference-in-Difference Analysis, 2002-2020 459 468 10.34172/hpp.45878 EN Seyede-Fereshte Hosseini https://orcid.org/0000-0001-9825-4727 Ali Imani Farhad Lotfi Behzad Najafi https://orcid.org/0000-0001-9479-3774 Journal Article 10.34172/hpp.45878 2026 04 26 2026 09 07 Introduction: Out-of-pocket (OOP) payment is an key indicator of financial burden in health. We assessed changes in per-capita OOP expenditures associated with Iran’s Urban Family Physician Program (UFPP), implemented in Fars and Mazandaran provinces in 2012, compared with aggregated non-intervention provinces. Methods: We conducted a quasi-experimental policy evaluation with difference-in-differences (DID) and interrupted time series (ITS) analyses using Statistical Center of Iran data for 2002–2020. Fars and Mazandaran were the intervention provinces; while the remaining provinces constituted the aggregated non-intervention comparison group. The outcome was annual per-capita household OOP expenditure at constant 2020 prices. DID estimated changes relative to the comparison series, while ITS estimated immediate level and post-intervention trend changes. Inference was based on Newey–West HAC standard errors. Results: In Fars, DID analysis indicate a significant decrease in per-capita OOP expenditures relative to the aggregated non-intervention comparison series (β3=−5,981; CI, −11,400 to −595; P=0.031). ITS showed a significant immediate level reduction (β6=−9,242; CI, −16,800 to -1.712; P=0.016), with no significantly change in trend (β7=−1,278; CI -2.623 to 68; P=0.063). In Mazandaran, no significant change was observed in aggregate OOP expenditures; however, service-specific analyses revealed heterogeneous changes across expenditure categories. Conclusion: UFPP implementation was associated with an immediate reduction in per-capita OOP expenditures, without a significant trend change in Fars and no significant aggregate change was observed in Mazandaran.