Responsiveness of health-related quality-of-life questionnaires in adults undergoing Strabismus surgery

Objective: To evaluate the responsiveness of 2 health-related quality-of-life (HRQOL) questionnaires, the Adult Strabismus-20 (AS-20) and National Eye Institute Visual Function Questionnaire-25 (VFQ-25), to changes in HRQOL after strabismus surgery.

Design: Cohort study.

Participants: We included 106 adults (aged 18-84 years; median, 48.5) undergoing strabismus surgery, 80 (75%) with diplopia and 26 (25%) without diplopia.

Methods: All participants completed AS-20 and VFQ-25 questionnaires preoperatively and a median of 7 weeks (range, 4-13) postoperatively. Using predefined clinical criteria, postoperative outcomes were graded as either "success" (n = 65), "partial success" (n = 32), or "failure" (n = 9).

Main outcome measures: For each questionnaire, mean composite and subscale scores (range, 0-100; worst to best HRQOL) were calculated for each patient. Median change in scores pre- to postoperatively was compared for successes, partial successes, and failures, and the proportion of patients whose scores exceeded 95% limits of agreement was calculated.

Results: Successfully aligned diplopic patients (n = 46) showed greater improvement than failures (n = 7) using both the AS-20 questionnaire (21.3 [quartiles 12.5-35.0] vs. 8.8 [3.8-12.5]; P = 0.002) and the VFQ-25 questionnaire (18.3 [8.6-26.1] vs 8.3 [0.8-13.5]; P = 0.02). Successfully aligned nondiplopic patients (n = 19) also showed greater improvement than failures (n = 2; AS-20, 23.8 [10.0-32.5] vs -3.1 [-10.0 to 3.8]; P = 0.05). In nondiplopic patients, changes on VFQ-25 were small but significantly greater for successes than failures (5.0 [0.0-10.1] vs -15.4 [-19.4 to -11.4]; P = 0.03). More successfully aligned patients showed improvement exceeding the 95% limits of agreement for AS-20 scores than VFQ-25 scores (67% vs 65% [P = 0.8] for diplopic patients and 63% vs 21% [P = 0.005] for nondiplopic patients).

Conclusions: The AS-20 and VFQ-25 questionnaires are responsive to improved HRQOL in adults undergoing successful strabismus surgery. Changes on VFQ-25 were smaller, particularly for nondiplopic strabismus. The AS-20 is more responsive than the VFQ-25 across the range of adult strabismus.