Use of a Matching Algorithm to Evaluate Hospital Coronary Artery Bypass Grafting Performance as an Alternative to Conventional Risk Adjustment

Published in: Medical Care, v. 45, no. 4, Apr. 2007, p. 292-299

Posted on on January 01, 2007

by Laurent G. Glance, Turner M. Osler, Dana B. Mukamel, Andrew W. Dick

Read More

Access further information on this document at Medical Care

This article was published outside of RAND. The full text of the article can be found at the link above.

BACKGROUND: Although public reporting of hospital and physician performance is a cornerstone of the effort to improve health care quality, the optimal approach to risk adjustment is unknown. OBJECTIVE: The authors sought to assess hospital quality using a matching algorithm based on a generalized distance metric and to compare this approach to the more traditional regression-based approach. DESIGN/ DATA SOURCE: This was a retrospective study using the New York State (NYS) Coronary Artery Bypass Surgery Reporting System (CSRS), focusing on all patients undergoing isolated CABG surgery in NYS who were discharged in 1999 (18,116 patients). Patients from specific hospital were matched to a control group using the Mahalanobis distance. The hospitals' expected mortality rate was calculated in 2 ways: (1) as the mortality rate of the control group or (2) as the mortality rate predicted by the NYS CABG model. Hospitals whose observed mortality rate was significantly different from their expected mortality rate (OE difference) were defined as quality outliers. RESULTS: The 2 risk-adjustment methodologies disagreed on the outlier status of 4 of the 33 hospitals. Kappa analysis demonstrated substantial agreement between these 2 methods for identifying quality outliers: [kappa] = 0.61. There was excellent agreement between the point estimates of the OE difference obtained using these 2 risk adjustment methodologies. CONCLUSION: Basing outcome assessment on either matching or regression modeling yielded similar findings on hospital ranking but only moderate level of agreement on hospital quality. The use of matching may enhance the transparency and acceptance of outcome report cards by hospitals and physicians.

This report is part of the RAND Corporation external publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.