The Stroke Upper and Lower Extremity Physical Function Measures Were Supported for Score Reliability, Validity, and Administration Efficiency for Patients Poststroke

Abstract

Abstract Objective The aims of this study were to (1) evaluate the suitability of newly developed items for calibration into 2 item banks for stroke upper extremity (SUE) and stroke lower extremity (SLE) physical function (PF) patient-reported outcome measures (PROMs) and to (2) assess score reliability and validity and PROM administration efficiency based on computerized adaptive testing (CAT). Methods A retrospective longitudinal study involving patients poststroke who were treated in outpatient rehabilitation clinics and responded to 28 and 25 region-specific candidate items addressing tasks related to upper or lower extremity PF, respectively, was conducted. Item response theory (IRT) model assumptions of unidimensionality, local independence, item fit, and presence of differential item functioning were evaluated. CAT-generated scores were assessed for reliability, validity, and administration efficiency, and 10-item short forms were assessed for reliability. Results Cohorts consisted of 2017 patients with stroke involving the upper extremity and 2107 patients with stroke involving the lower extremity (mean age [SD]: SUE = 62 [14] and SLE = 63 [14]; range = 14–89). Two solutions (SUE: 28-item; SLE: 24-item) supported unidimensionality and fit to the IRT model, with reliability estimates >0.93 for all administration modes. No items demonstrated differential item functioning. Scores discriminated among multiple patient groups in clinically logical ways, with better outcomes observed for patients who were younger, were male, had less chronicity, and had fewer comorbidities. The SUE and SLE, respectively, had 1 and 0.3% floor effects and 4.3 and 1.1% ceiling effects. Change score effect sizes were 0.5 (SUE) and 0.6 (SLE). Simulated CAT scores required an average of 6 (SUE) and 5.6 (SLE) items (median = 5). Conclusion The stroke upper extremity and stroke lower extremity PROM scores were reliable, valid, and efficient and had moderate change effect sizes for assessing PF as perceived by patients poststroke with upper and lower extremity impairments. Scores had negligible floor and acceptable ceiling effects. Based on these results, the stroke PROMs are suitable for research and routine clinical practice. Impact As IRT-based measures, these PROMs support clinical practice guideline recommendations for the use of outcome measures in neurologic physical therapy and the administration of condition-specific functional questions with low response burden for patients. The 10-item short forms offer a feasible alternative administration mode when CAT administration is not available.