The watery eye quality of life (WEQOL) questionnaire: a patient-reported outcome measure for surgically amenable epiphora

Abstract

Objective or purpose: To develop and test a patient-reported outcome measure for assessing health-related quality of life (HRQOL) in surgically amenable epiphora. Design: Questionnaire development and validation study. Participants: 201 patients with a cause of epiphora amenable to surgical intervention, recruited across three independent centres. Methods, intervention or testing: The watery eye quality of life (WEQOL) questionnaire was developed and refined according to defined psychometric standards. Both surgical and non-surgical participants completed WEQOL at baseline and follow-up (>3 months), along with the Lacrimal Symptom Questionnaire (Lac-Q), RAND Short Form Health Survey (SF-36) and Glasgow Benefit Inventory (GBI). Convergent validity of WEQOL was evaluated according to correlation (R > 0.40) with each of these additional tests. Responsiveness of WEQOL to intervention was evaluated according to patient-reported success. Test-retest reliability was assessed by the Bland–Altman method and intraclass correlation (ICC) in a subset of 64 participants at baseline. Main outcome measures: WEQOL construct validity, responsiveness and test-retest reliability. Results: WEQOL was moderately correlated (R > 0.4) with the Lac-Q and several subscales of the SF-36 (physical role limitation, social, emotional role limitation and emotional well-being). A stronger correlation was found between the change in WEQOL at follow-up and GBI (R = 0.61). An appropriate graded response was found with a significant change in WEQOL score being observed in patients reporting successful (−28%, p < 0.0001) and partially successful surgery (−6%, p = 0.04), but not in those reporting unsuccessful surgery (+2%, p = 0.9). High test-retest reliability was observed (ICC = 0.93). Conclusions: The WEQOL questionnaire has been developed systematically according to modern psychometric standards and has been designed to evaluate the quality of life in patients with epiphora that is of a surgically amenable cause. In this study, it has demonstrated appropriate test-retest reliability, responsiveness and construct validity.