Do HMOs make a difference? Use of health services

This study analyzes the effects of health maintenance organization (HMOs) on the use of health services by the privately, insured, nonelderly population. After controlling for population and location differences, HMOs increase physician visits, nonphysician practitioner visits, ann total ambulatory visits by modest but significant margins girls, while shifting the mix of physician care front specialists to primary care physicians. HMOs also increase use of two preventive services: mammography screening and flu shots. Contrary to expectation, however, the study finds no significant differences between HMO and non-HMO enrollees in the rise of hospital, surgery, and emergency room services.