Are HMO enrollees healthier than others? Results from the community tracking study.

This analysis addresses the question of biased selection into health maintenance organizations (HMOs) by using recent, nationally representative data from the Community Tracking Study (CTS) to compare the health status of nonelderly privately insured persons enrolled in HMO and non-HMO plans. Contrary to the conventional view that HMOs receive favorable selection, we find among the privately insured that HMO enrollees are not healthier and may be slightly less healthy. To help understand that result, we present evidence suggesting that other factors, including cost considerations, may be more important than health when people are deciding whether to enroll in an HMO.