Relationship of size and payment mechanism to system performance in 11 medical care systems.

The performance of 11 medical care systems of varying size and payment mechanisms (consisting of six government owned and operated Indian Health Service units, three fee-for-service private practices and two HMOs) was studied. Performance was defined as the percentage of consumers in need of care who received adequate care according to predetermined standards for the process of care for various functions (i.e., prevention, screening, treatment, follow-up) and various health conditions (i.e., prenatal and infant care, hypertension, anemia, UTI). Size was found to have a strong negative relationship to the quality of treatment and follow-up care, but payment mechanism did not show such a relationship. Neither size nor payment mechanism was significantly related to prevention performance. In screening, the results depended on the health condition: size was inversely related to performance of screening for hypertension; HMOs performed significantly better in screening for prenatal anemia; and neither size nor payment mechanism was related to performance of screening for infant anemia.