Determining the minimal important change in patient reported outcomes for carpal tunnel syndrome.

Abstract

Patient reported outcome measures (PROMs) can be used to quantify responses to treatment and for quality measurement purposes. However, the clinical importance of a given change in a PROM score is hard to interpret. The minimal important change (MIC) is the smallest change in score that patients consider important. To estimate MICs for three PROMs at 3- and 9-month follow-ups for a large five-institution sample of patients with carpal tunnel syndrome. Cohort study. Two university, two Veterans Affairs, and one community nonprofit health care systems. Patients receiving initial consultation with a hand surgeon for carpal tunnel syndrome. Patients completed baseline, 3-month, and 9-month PROMs: the Boston Carpal Tunnel Questionnaire Symptom (BCTQ-SS) and Functioning (BCTQ-FN) Scales, and the Quick Disabilities of the Arm, Shoulder, and Hand (QDASH) scale. Anchor-based methods and Youden J-statistics were used to find the optimal MIC cut points that maximized sensitivity and specificity for patients being satisfied with the outcome of treatment. Six hundred thirty-five patients completed the baseline PROMs, and 551 (87%) and 516 (81%) completed the 3- and 9-month PROMs, respectively. The percentage of patients who were at least somewhat satisfied with the results of treatment differed between the carpal tunnel release and nonoperative subgroups (91% vs. 67% at 9 months), as did the MIC estimates. At 9 months, 295 of 326 (91%) of carpal tunnel release patients were satisfied with the results of treatment, with MICs of 0.81, 0.66, and 15.7 for the BCTQ-SS, BCTQ-FN, and QDASH, respectively. We also produced MICs for the 3-month assessment, the nonoperative, and overall samples. These MIC estimates can be used in clinics or research to gauge response to treatment and used in the design of PROM-based quality measures.