An Evaluation of the Responsiveness and Discriminant Validity of Shoulder Questionnaires among Patients Receiving Surgical Correction of Shoulder Instability

Abstract

Health-related quality-of-life (HRQL) measures must detect clinically important changes over time and between different patient subgroups. Forty-three patients (32 M, 13 F; mean age  =  26.00  ±  8.19 years) undergoing arthroscopic Bankart repair completed three validated shoulder questionnaires (Western Ontario Shoulder Instability index (WOSI), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment form (ASES), Constant score) preoperatively, and at 6, 12, and 24 months postoperatively. Responsiveness and discriminant validity was assessed between those with a satisfactory outcome and those with (1) a major recurrence of instability, (2) a single episode of subluxation, (3) any postoperative episode of instability. Eight (20%) patients reported recurrent instability. Compared to baseline, the WOSI detected improvement at the 6- (P<0.001) and 12-month (P=0.011) evaluations. The ASES showed improvement at 6 months (P=0.003), while the Constant score did not report significant improvement until 12 months postoperatively (P=0.001). Only the WOSI detected differential shoulder function related to shoulder instability. Those experiencing even a single episode of subluxation reported a 10% drop in their WOSI score, attaining the previously established minimal clinically important difference (MCID). Those experiencing a frank dislocation or multiple episodes of subluxation reported a 20% decline. The WOSI allows better discrimination of the severity of postoperative instability symptoms following arthroscopic Bankart repair.