Background: Establishing the minimal clinically important difference for patient-reported outcomes questionnaires is essential in outcomes research to evaluate the patient’s perspective of treatment effectiveness. The authors aim to determine the minimal clinically important difference after carpal tunnel release in diabetic and nondiabetic patients using the Boston Carpal Tunnel Questionnaire.
Methods: The authors prospectively evaluated 114 patients (87 nondiabetic and 27 diabetic patients) undergoing carpal tunnel release. In addition to standard history and physical examination, the authors obtained preoperative electrodiagnostic studies to confirm carpal tunnel syndrome. The Boston Carpal Tunnel Questionnaire was administered before and after surgery at 3 and 6 months. Patients were asked about their level of satisfaction at the final follow-up visit. The authors applied the receiver operating characteristic curve approach to determine the minimal clinically important difference of symptom and function severity scales of the questionnaire. The authors used patient satisfaction as the reference standard to compare against the standardized change in scores after surgery for the two groups.
Results: For both diabetic and nondiabetic patients, symptom and function severity scales showed large effect sizes of greater than 0.8 at 3 and 6 months after surgery. At 6 months after surgery, to be satisfied, diabetic patients required a minimal clinically important difference of 1.55 and 2.05 for symptom and function scales, respectively, whereas nondiabetic patients required 1.45 and 1.6, respectively.
Conclusions: Diabetic patients needed a greater improvement in Boston Carpal Tunnel Questionnaire score to be satisfied on functional and symptom severity scales than nondiabetic patients. Overall, diabetic patients had less improvement in Boston Carpal Tunnel Questionnaire final scores compared with nondiabetics.
CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.