PROFILING OUTCOMES OF AMBULATORY CARE - CASEMIX AFFECTS PERCEIVED PERFORMANCE

OBJECTIVES. The authors explored the role of casemix adjustment when p rofiling outcomes of ambulatory care. METHODS. The authors reviewed th e medical records of 656 patients with hypertension, diabetes, or chro nic obstructive pulmonary disease (COPD) receiving care at one of thre e Department of Veterans Affairs medical centers. Outcomes included me asures of physiological control for hypertension and diabetes, and of exacerbations for COPD. Predictors of poor outcomes, including physica l examination findings, symptoms, and comorbidities, were identified a nd entered into regression models. Observed minus expected performance was described foreach site, both before and after casemix adjustment. RESULTS. Risk-adjustment models were developed that were clinically p lausible and had good performance properties. Differences existed amon g the three sites in the severity of the patients being cared for. For example, the percentage of patients expected to have poor blood press ure control were 35% at site 1, 37% at site 2, and 44% at site 3 (P < 0.01). Casemix-adjusted measures of performance were different from un adjusted measures. Sites that were outliers (P < 0.05) with one approa ch had observed performance no different from expected with another ap proach. CONCLUSIONS. Casemix adjustment models can be developed for ou tpatient medical conditions. Sites differ in the severity of patients they treat, and adjusting for these differences can alter judgments of site performance. Casemix adjustment is necessary when profiling outp atient medical conditions.