Development of Item Pools to Assess the Impact of Diabetic Retinopathy on Quality of Life

Abstract

Purpose: : There is no existing patient reported outcome (PRO) measure to comprehensively assess the impact of diabetic retinopathy (DR) on quality of life (QoL). We have developed DR-specific item pools representing key QoL parameters that will become the world’s first calibrated item bank for DR.

Methods: : Item pool development comprised 6 distinct phases: a) qualitative interviews with patients with DR and eye professionals exploring the impact of DR on QoL; b) thematic analysis of qualitative interviews using an inductive analytical approach; c) data extraction from validated PRO measures and qualitative articles; d) generation of an initial item set; e) item reduction via winnowing and binning; f) development of item stems and response options.

Results: : 8 focus groups and 23 individual interviews were conducted. 57 patients (mean±SD age 58.7±11.6 yr; 68% male) and 7 eye professionals participated. Of the patients, 29% had presenting visual acuity worse than 6/12, 48% had proliferative DR, 44% had diabetic macular edema (ME) and 25% had clinically significant ME, all in the better eye. Thematic analysis of the focus groups produced 722 items. Novel findings included the ‘practical and emotional’ impact of DR-related treatment on patients’ QoL and the impact of DR on patients’ ability to ‘manage their diabetes’. A systematic review of 35 DR-related PRO measures and 4 published qualitative studies produced 586 and 170 items, respectively. Combined, the initial item set comprised 1190 items. Items were then retained, removed or combined based on key selection criteria. A final set of 603 items and 48 themes remained, categorised into 5 domains, namely Functioning (165); Mobility (98); Symptoms & Treatment (95); Emotional (130) and; Social (115). Each item had four response options.

Conclusions: : Using a rigorous developmental strategy, we have produced 5 conceptually relevant item sets which will be valuable in assessing the impact of DR and the efficacy of treatment modalities on QoL.

Keywords: diabetic retinopathy • quality of life • low vision