comparison of the thresholds of households’ exposure to catastrophic health expenditure in iran and brazil, and selection of the most appropriate threshold

Background: different definitions are nowadays adopted to estimate the threshold of exposure of households to catastrophic health expenditures and different thresholds are used in various studies. this study was con-ducted to compare these thresholds and select the most appropriate threshold for defining catastrophic health expenditure in iran and brazil. methods: in this cross-sectional study, data were collected from 592 households from district 17 of tehran, iran, and 869 households from porto alegre, brazil in 2013. firstly, catastrophic health expenditures were cal-culated using two common proportions, i.e. out-of-pocket health payments, as a proportion of total cost and as a proportion of ability to pay. these proportions were analysed using the receiver operating characteristic (roc) curve and kappa coefficient. results: the appropriate cut off point for the thresholds of 5%, 10%, 15%, and 20% of the total expenditure was 0.52, 0.34, 0.28, and 0.46 in iran, and 0.44, 0.36, 0.28, and 0.23 in brazil, respectively. the appropriate cut off point for the thresholds of 20%, 25%, 30%, 35%, and 40% of ability to pay was 0.31, 0.28, 0.25, 0.34, and 0.40 in iran and 0.36, 0.34, 0.30, 0.38, and 0.46 in brazil, respectively. conclusion: the appropriate cut off point for the proportion of out-of-pocket health payments to total ex-penditure and proportion of health expenditure to ability to pay was the threshold of 20% of total expenditure and 35% of ability to pay, respectively.