Preventable hospitalizations and socioeconomic status.

"Preventable" hospitalizations have been proposed as indicators of poor health plan performance. In this study of elderly Medicare beneficiaries, however, we found that preventable hospitalizations are also more common among elders of lower socioeconomic status (SES). The relationship persisted even when an up-to-date severity-of-illness adjustment system was used. To the extent that indicators of health plan "performance" reflect enrollees' characteristics, plans will be rewarded for marketing their services to wealthier, healthier, and better-educated patients. Further work is needed to clarify issues of accountability for preventable hospitalizations and other putative indices of health plan performance.