Case-Mix Adjustment Using Administrative Databases: A Paradigm to Guide Future Research

Abstract

One of the most persistent problems in the field of quality assessment remains how to remove the confounding effect of different institutions providing care to patients with dissimilar severity of illness and case complexity. The authors review the literature to determine whether risk adjustment systems based on administrative data are inherently inferior to systems that depend on primary data collection and conclude that they are not. In light of the potential competence of risk adjustment systems based on administrative data, the authors identify those systems that are best supported by theory and evidence. Data elements that have been found most explanatory of medical outcomes are also identified. On the basis of an evaluation of the performance of various risk adjustment approaches, the authors propose a paradigm that could serve to unify and direct future studies.

Waiting times and socioeconomic status: Evidence from England

“…This might be due to measurement error in reporting patient's primary diagnosis within hospital, i.e. some hospitals might be less accurate than others in identifying the correct patient's diagnosis in a basket of similar conditions (Wray et al, 1997).…”

Spatial disparities in hospital performance

“…Indeed, evidence shows that the effect of characteristics on mortality is disease-specific (Wray et al, 1997). We select the Acute Myocardial Infarction (heart attack) for four reasons.…”

Estimating the quality of care in hospitals using instrumental variables

“…13 See Wray et al (1997). 14 Pneumonia is also the leading cause of death among patients with nosocomial (hospital acquired) infections (Pennington (1994)).…”

“…Wray et al (1997) advise that appropriate adjustment mechanisms must control for the principle diagnosis within a DRG, contain demographics as proxies for pre-existing physiological reserve, and measure the number and severity of comorbidities. Following Iezzoni (1994), we control for the principle diagnosis and the measure of comorbidities using dummies for the Disease Stage.…”

“…We follow the suggestions of Wray et al (1997) and Iezzoni (1994) in constructing the set of explanatory variables, i…”