Abstract
Purpose: :
To compare the responsiveness of 2 health related quality of life (HRQOL) instruments, the new strabismus-specific AS-20 and the NEI VFQ-25, in adults undergoing strabismus surgery.
Methods: :
37 adults with strabismus (aged 21 to 82 years, median 51) who were successfully aligned postoperatively, completed the AS-20 and VFQ-25 preoperatively and a median of 8 weeks postoperatively (range 4 to 13 weeks). 25 patients had diplopia, and 12 had no diplopia. Each questionnaire (overall and subscales) was scaled from 0 (worst HRQOL) to 100 (best HRQOL). 95% limits of agreement (LOA) for both AS-20 and VFQ-25 were defined in a previous test-retest study and real change in HRQOL was defined as change exceeding the 95% LOA. We compared proportions of patients showing real change.
Results: :
Overall, more patients showed an improvement in AS-20 score compared to composite VFQ-25 score (21 [58%] of 37 vs 11 [30%]; P=0.01). Analyzing by whether the patient had diplopia or not, more patients without diplopia showed improvement in AS-20 than VFQ-25 (7 [58%] of 12 vs 0 of 12). On AS-20 subscales, 8 (67%) of 12 improved on the psychosocial subscale and 1 (8%) improved on the function subscale. On the 5 potentially useful VFQ-25 subscales (identified in a previous study), only 2 (17%) of 12 non-diplopic patients improved on Vision-specific (VS) role difficulties and VS social functioning subscales, and only 1 (8%) improved on VS dependancy; no patients showed improvement on the VS mental health and Peripheral vision subscales. In contrast, for diplopic patients, the AS-20 and VFQ-25 were more comparable. Similar proportions showed improvement in composite AS-20 and VFQ-25 scores (14 [56%] of 25 vs 11 [44%]; P=0.3). On AS-20 subscales, 10 (40%) of diplopic patients improved on the function subscale and 6 (24%) improved on the psychosocial subscale. On the 5 potentially useful VFQ-25 subscales, the proportion of diplopic patients showing improvement ranged from 54% to 12%: VS role difficulties: 13 (54%) of 25, VS mental health: 12 (48%), VS dependancy: 8 (32%); VS social functioning: 5 (20%), and Peripheral vision 3 (12%).
Conclusions: :
For non-diplopic patients, the AS-20 is more responsive than the VFQ-25 to improvement in HRQOL following strabismus surgery. For diplopic patients both questionnaires are responsive. The new strabismus-specific AS-20 questionnaire is useful over the entire spectrum of strabismus and addresses both function and psychosocial issues.
Keywords: strabismus • esotropia and exotropia • quality of life