Risk adjustment and primary health care in Chile.

AIM: To offer a capitation formula with greater capacity for guiding resource spending on population with poorer health and lower socioeconomic status in the context of financing and equity in primary health care.
METHODS: We collected two years of data on a sample of 10,000 individuals from a region in Chile, Valdivia and Temuco and evaluated three models to estimate utilization and expenditures per capita. The first model included age and sex; the second one included age, sex, and the presence of two key diagnoses; and the third model included age, sex, and the presence of seven key diagnoses. Regression results were evaluated by R2 and predictive ratios to select the best specifications.
RESULTS: Per-capita expenditures by age and sex confirmed international trends, where children under five, women, and the elderly were the main users of primary health care services. Women sought health advice twice as much as men. Clear differences by socioeconomic status were observed for the indigent population aged > or =65 years who under-utilized primary health care services. From the three models, major improvement in the predictive power occurred from the demographic (adjusted R2, 9%) to the demographic plus two diagnoses model (adjusted R2, 27%). Improvements were modest when five other diagnoses were added (adjusted R2, 28%).
CONCLUSION: The current formula that uses municipality's financial power and geographic location of health centers to adjust capitation payments provides little incentive to appropriate care for the indigent and people with chronic conditions. A capitation payment that adjusts for age, sex, and the presence of diabetes and hypertension will better guide resource allocation to those with poorer health and lower socioeconomic status.