Do HMOs Make a Difference?

Use of Health Services

Winter 1999/2000
Inquiry , vol.36, no.4 (Winter 1999/2000): 400-410
Ha T. Tu, Peter Kemper, Holly L. Wong


his study analyzes the effects of health maintenance organizations (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, and total ambulatory visits by modest but significant margins, while shifting the mix of physician care from 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 use of hospital, surgery, and emergency room services.

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