Statistics in the News: Chapter 17 Multiple Regression and Correlation

Hospital Volume and Surgical Mortality

Using information about 2.5 million cases in the national Medicare claims data base, researchers examined the mortality associated with six different types of cardiovascular procedures and eight types of major cancer resections between 1994 and 1999. Multiple regression techniques were used to relate hospital volume (total number of procedures performed per year) to mortality (in-hospital or within 30 days), adjusted for other patient characteristics.

Mortality decreased as volume increased for all 14 types of procedures, but the relative importance of volume varied markedly according to the type of procedure. Crucial results are summarized in Table A.

TABLE A Adjusted Mortality Rates (%)

Conclusion: In the absence of other information about the quality of surgery at particular hospitals, Medicare patients undergoing cardiovascular or cancer procedures can significantly reduce their risk of operative death by selecting high-volume hospitals.

Sources: Adapted from John D. Birkmeyer et al., "Hospital Volume and Surgical Mortality in the United States," The New England Journal of Medicine, April 11, 2002, pp. 1128-1137, and Arnold M. Epstein, "Volume and Outcome-It Is Time To Move Ahead," ibid., pp. 1161-1164.