Adaptive Measurement of Change: A Novel Method to Reduce Respondent Burden and Detect Significant Individual-Level Change in Patient-Reported Outcome Measures

Objective: To describe the adaptive measurement of change (AMC) as a means to identify psychometrically significant change in reported function of hospitalized patients and to reduce respondent burden on follow-up assessments. Design: The AMC method uses multivariate computerized adaptive testing (CAT) and psychometric hypothesis tests based in item response theory to more efficiently measure intra-individual change using the responses of a single patient over 2 or more testing occasions. Illustrations of the utility of AMC in clinical care and estimates of AMC-based item reduction are provided using the Functional Assessment in Acute Care Multidimensional Computerized Adaptive Test (FAMCAT), a newly developed functional multidimensional CAT-based measurement of basic mobility, daily activities, and applied cognition. Setting: Two quaternary hospitals in the Upper Midwest. Participants: Four hundred ninety-five hospitalized patients who completed the FAMCAT on 2 to 4 occasions during their hospital stay. Intervention: N/A. Results: Of the 495 patients who completed more than 1 FAMCAT, 72% completed 2 sessions, 13% completed 3, and 15% completed 4, with 22.1%, 23.4%, and 23.0%, respectively, exhibiting significant multivariate change. Use of the AMC in conjunction with the FAMCAT reduced respondent burden from that of the FAMCAT alone for follow-up assessments. On average, when used without the AMC, 22.7 items (range, 20.4-24.4) were administered during FAMCAT sessions. Post hoc analyses determined that when the AMC was used with the FAMCAT a mean±standard deviation reduction in FAMCAT number of items of 13.6 (11.1), 13.1 (9.8), and 18.1 (10.8) would occur during the second, third, and fourth sessions, respectively, which corresponded to a reduction in test duration of 3.0 (2.4), 3.0 (2.8), and 4.7 (2.6) minutes. Analysis showed that the AMC requires no assumptions about the nature of change and provides data that are potentially actionable for patient care. Various patterns of significant univariate and multivariate change are illustrated. Conclusions: The AMC method is an effective and parsimonious approach to identifying significant change in patients’ measured CAT scores. The AMC approach reduced FAMCAT sessions by an average of 12.6 items (55%) and 2.9 minutes (53%) among patients with psychometrically significant score changes.