Regional variation in Medicare hospital mortality.

This study examines variation in severity-adjusted Medicare hospital mortality rates across nine U.S. census regions. The extent to which regional variation is reduced by controlling for differences in hospital resources and structure, county-level population characteristics, and the level of federal SuperPRO-identified hospital quality problems is estimated. Hospital resources, population characteristics, and SuperPro process quality scores are significant predictors of hospital mortality rates, but they do not explain the important, highly significant regional differences observed after controlling for hospital case-mix severity.