Objective. To assess the impact on fair health financing and household catastrophic health expenditures of the implementation of the Popular Health Insurance (Seguro Popular de Salud). Material and Methods. Data analyzed in this study come from the National Income and Expenditure Household Survey (Encuesta Nacional de Ingresos y Gastos de los Hogares, ENIGH), 2000, and the National Health Insurance and Expenditure Survey, (Encuesta Nacional de Aseguramiento y Gasto en Salud, ENAGS), 2001. Estimations are based on projections of extension of the Popular Health Insurance under different conditions of coverage and out-of-pocket expenditure reductions in the uninsured population. The mathenatic simulation model assumes applying the new Popular Health Insurance financial structure to the 2000 expenditure values reported by ENIGH, given the probability of affiliation by households. Results. The model of determinants of affiliation to the Popular Health Insurance yielded three significant variables: being in income quintiles I and II, being a female head of household, and that a household member had a medical visit in the past year. Simulation results show that important impacts on the performance of the Mexican Health System will occur in terms of fair financing and catastrophic expenditures, even before achieving the universal coverage goal in 2010. A reduction of 40% in out-of-pocket expenditures and a Popular Health Insurance coverage of 100% will decrease catastrophic health expenditures from 3.4% to 1.6%. Conclusions. Our results show that the reduction of out-of-pocket expenditures generated by the new financing and health provision Popular Health Insurance model, will improve the financial fairness, index and the financial contribution to the health system and will decrease the percentage of households with catastrophic expenditures, even before reaching universal coverage. A greater impact may be expected due to coverage extension initiating in the poorest communities that have 2. very restricted and progressive financial contribution.
