Do HMOs make a difference? Introduction

The study presented in this and the following five papers analyzes how heal th maintenance organizations (HMOs) affect privately insured individuals' a ccess to health cal-e, use of services, and assessments of care. Using a co mmon data source and methodology, the study examines differences in a broad range of measures between HMOs and other types of insurance, controlling f or health status and an extensive set of other individual characteristics a nd market location. HMO-non-HMO differences also are examined across popula tion subgroups defined by health status, income, race, and age. Data come f rom the Community, Tracking Study Household Survey, a recent, large nationa l survey. Findings show that a person's type of health insurance coverage h as little effect on the likelihood of unmet or delayed needs for medical ca re in the aggregate, brit the types of access problems faced Dy HMO and non -HMO enrollees differ. HMO enrollees are less likely to face financial barr iers to care, but more likely to face barriers related to the organization of care delivery. HMO enrollees use more ambulatory and preventive care, bu t results show no differences in hospital, surgery and emergency room use. Compared with other types of insurance physician visits under HMOs are more likely to be to primary care physicians than to specialists. Finally, acro ss nearly all measures of patients' satisfaction, ratings of their. last do ctor's visit, and trust in their physicians, HMO enrollees' assessments of of care are lower than those of people not in HMOs. Across all measures, ri te study finds few subgroup differences.