Risk adjustment models for hospitalized patients are most advanced for the assessment of the clinical outcome of cardiac procedures, and for coronary artery bypass grafting in particular. The goal of being able to use outcomes as a credible indicator of quality of care has stimulated the development of several programs that use reliable, valid patient data collected during the surgical episode to adjust outcomes for the severity of illness. Several criteria that are useful in the assessment of risk adjustment methods for outcome and quality-of-care investigations are discussed in detail and five of these programs are compared. The programs have more similarities than differences and identify many of the same patient characteristics predictive of a higher likelihood of mortality in the period immediately after operation. Whether persistent differences in mortality after risk adjustment across institutions or individual surgeons, or both may ultimately be attributed to the process and structure of care needs further study and investigation. Similar methods should be applied to other outcomes of importance to patients, their families, and their physicians, such as surgically related morbidity, functional status, quality of life, costs, and patient-reported perceptions of the nontechnical aspects of their care.
