HEDIS measures and managed care enrollment

This article examines the relationship between 1996 health plan enrollment and both HEDIS-based plan performance ratings and individual HEDIS measures . Data were obtained from a large firm that collected, aggregated, and diss eminated plan performance ratings to its employees. Plan market share regre ssions are estimated controlling for out-of-pocket price and model type in addition to the plan ratings and HEDIS measures. The results suggest that e mployees did not respond strongly to the provided ratings. There are severa l potential explanations for the lack of response, including difficulty und erstanding the ratings and never having seen them. In addition, employees m ay base their plan choices on information that is obtained from their own p ast experience, friends, family, and colleagues. The pattern of results sug gests that such information is important. Counterintuitive signs most likel y reflect an inverse correlation between some HEDIS ratings (or measures) a nd attributes employees observe informally.