Development of a Risk-adjustment Model for the Inpatient Rehabilitation Facility Discharge Self-care Functional Status Quality Measure

Background: Functional status measures are important patient-centered indicators of inpatient rehabilitation facility (IRF) quality of care. We developed a risk-adjusted self-care functional status measure for the IRF Quality Reporting Program. This paper describes the development and performance of the measure's risk-adjustment model. Methods: Our sample included IRF Medicare fee-for-service patients from the Centers for Medicare & Medicaid Services' 2008-2010 Post-Acute Care Payment Reform Demonstration. Data sources included the Continuity Assessment Record and Evaluation Item Set, IRF-Patient Assessment Instrument, and Medicare claims. Self-care scores were based on 7 Continuity Assessment Record and Evaluation items. The model was developed using discharge self-care score as the dependent variable, and generalized linear modeling with generalized estimation equation to account for patient characteristics and clustering within IRFs. Patient demographics, clinical characteristics at IRF admission, and clinical characteristics related to the recent hospitalization were tested as risk adjusters. Results: A total of 4769 patient stays from 38 IRFs were included. Approximately 57% of the sample was female; 38.4%, 75-84 years; and 31.0%, 65-74 years. The final model, containing 77 risk adjusters, explained 53.7% of variance in discharge self-care scores (P<0.0001). Admission self-care function was the strongest predictor, followed by admission cognitive function and IRF primary diagnosis group. The range of expected and observed scores overlapped very well, with little bias across the range of predicted self-care functioning. Conclusions: Our risk-adjustment model demonstrated strong validity for predicting discharge self-care scores. Although the model needs validation with national data, it represents an important first step in evaluation of IRF functional outcomes.