Item response theory and computerized adaptive testing: Implications for outcomes measurement in rehabilitation

Objective: To evaluate computerized adaptive testing (CAT) measures of rehabilitation outcomes. Study Design: Physical functioning questions were calibrated via item response theory (IRT) and administered with CAT software. Subjects: 485 adults interviewed during postacute care rehabilitation (simulation study) and 26 adults who completed CAT and personal interviews (CAT pilot study). Main Outcome Measures: Patient acceptance and respondent burden, reliability, and discriminant validity. Results: In the simulation study, CAT-based estimates correlated highly (r =.93 and r =.98) with criteria, minimized ceiling and floor effects, and reduced respondent burden while achieving high reliability. Pilot study patients preferred self-administered CAT surveys, and CAT scores discriminated well across severity levels. Conclusions: CAT software has considerable potential to improve physical functioning measurement in rehabilitation settings.