Affiliations: [a] Department of Community and Preventive Medicine,
University of Rochester, Rochester, NY, USA | [b] Center for Organization and Delivery Studies, Agency
for Healthcare Research and Quality, Rockville, MD, USA
Correspondence:
[*]
David Stewart Associate Professor of Health
Policy, Department of Community and Preventive Medicine, University of Rochester
Medical Center, 601 Elmwood Avenue, Box 644, Rochester, NY 14642, USA. Tel.: +1
716 275 1985; Fax: +1 716 461 4532; E-mail:
Dana_Mukamel@urmc.rochester.edu
Abstract: Governments and private organizations have recently begun publishing "report
cards" that compare quality of hospitals, physicians and health care plans.
Often these reports include quality measures based on risk adjusted health
outcomes of the patients treated by each health care provider. The use of these
measures is, however, controversial due to concerns about their accuracy.
To-date, concerns focused on the risk adjustment methodology and small sample
sizes. We raise an additional issue related to the definition of quality
measures as either the difference between observed and predicted outcome rates
or the ratio between these rates. A theoretical analysis of the properties of
the two measures is presented. Monte Carlo simulations quantify the effects
identified in the theoretical analysis. We show that the two risk adjusted
outcome measures of quality may lead to different conclusions about relative
quality among providers. Which measure should be used depends on the underlying
relationship between patient risks and quality of care in determining health
outcomes. For the case replicating the HCFA hospital mortality statistics, the
percent of true outliers identified by the incorrect measure ranges from 64%
78%. than health care, where performance is measured based on outcomes.
Keywords: quality of care, risk-adjusted outcomes, quality assessment, quality measurement, quality report cards
