Effects of funding of rural tribally-operated health programs on health outcomes of AI/AN

Objective: To determine whether Indian Health Service (IHS) funding of rural Tribally-Operated Health Programs (TOHP) affects preventable hospitalizations of American Indian/Alaska Natives (AIAN) who use them. TOHP are one of three types of Service Units funded by the IHS. Owned by sovereign tribes, TOHP provide comprehensive primary care, but usually must contract for specialty and hospital care. Methods: Records in the IHS National Patient Information Registry System of an annual average 42,153 AIAN Active Users of TOHP from 1998 to 2002 in California were linked with state hospital discharge records. We analyzed 3,181 preventable hospitalizations of AIAN users of 20 TOHP in California using Poisson regression models and GEE to control for age and gender and to account for clustering. The dependence of the preventable hospitalizations on the IHS Federal Disparity Index (FDI) developed by the IHS was studied. We investigated: 1) the FDI effect on the outcome; 2) which components of the FDI determine the effect; 3) whether patient volume, service type or quality of care (GPRA) indicators mediate the effect; 4) what rural community characteristics of service areas confound the effect including: demand for services, Indian Gaming revenues and disparities with Whites in education, income, employment, transportation, telephones and crowding. Findings: IHS funding of TOHP had a robust effect on preventable hospitalizations of AIAN who use them, even after controlling for characteristics of their rural service areas. For TOHP with less than 60% of health care costs funded, the preventable hospitalization rate dropped 12% for every increase of 10% of costs funded (P=0.011). After controlling for community characteristics, the funding effect remained significant (0.01