Development of a Concise Patient-Reported Outcome Measure for Cataract Surgery in South India

Abstract

Purpose : Existing patient-reported outcome measures (PROMs) for cataract surgery are too long to be employed in a busy clinical setting or are not culturally relevant to patients in South India. Consequently, we prospectively surveyed patients in order to develop and test the psychometric properties of a shortened version of the Indian Visual Functioning Questionnaire (IND-VFQ-SF) for patients undergoing cataract surgery in Tamil Nadu, India.

Methods : In Phase 1, using the full Rasch-modified IND-VFQ we prospectively surveyed patients undergoing cataract surgery preoperatively and 1 month postoperatively. We calculated the effect size of each of the 28 survey items (Cohen’s d) and correlations between item scores and preoperative visual acuity. An expert panel (AH, JDS, JRE) selected items from each subscale that were deemed relevant to patients with cataracts and that had: Cohen’s d >0.5; >35% of respondents affected; and correlation with vision in the better-seeing eye <-0.15. Selected items formed the IND-VFQ-SF. In Phase 2, the resulting IND-VFQ-SF was prospectively administered to a separate group of patients undergoing cataract surgery. Cronbach’s α and item-total correlations were calculated to evaluate the reliability of the IND-VFQ-SF. For both study phases patients were recruited in even proportions from Aravind’s private and charity hospitals.

Results : In Phase 1, 212 patients completed the full IND-VFQ questionnaire. Using predefined criteria and expert consensus, 12 survey items were selected to comprise the IND-VFQ-SF; these items were related to mobility, activity limitation, psychosocial impact, and visual symptoms. In Phase 2, the 12-item survey was completed by an additional 225 patients before and after cataract surgery. The mean age of patients in Phase 2 was 60.4 ± 8.6 years; they were 66.2% female; 36.4% had no formal schooling; 58.5% had a monthly income ≤ 5000 Rupees (US$73); and 53.9% underwent manual small-incision cataract surgery. Mean LogMAR visual acuity was 0.48 preoperatively and 0.06 post-operatively. Cronbach’s α was 0.85 and item-total correlations ranged from 0.47 to 0.74.

Conclusions : The IND-VFQ-SF we developed was found to have high internal consistency and its items had very good discriminating power. Thus, this instrument was found to be a reliable PROM to assess the success of cataract surgery in South India.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.