Validation of a New Diabetic Retinopathy Knowledge and Attitudes Questionnaire in People with Diabetic Retinopathy and Diabetic Macular Edema.

Purpose: A validated questionnaire assessing diabetic retinopathy (DR)- and diabetic macular edema (DME)-related knowledge (K) and attitudes (A) is lacking. We developed and validated the Diabetic Retinopathy Knowledge and Attitudes (DRKA) questionnaire and explored the association between K and A and the self-reported difficulty accessing DR-related information (hereafter referred to as Access). Methods: In this mixed-methods study, eight focus groups with 36 people with DR or DME (mean age, 60.1 ± 8.0 years; 53% male) were conducted to develop content (phase 1). In phase 2, we conducted 10 cognitive interviews to refine item phrasing. In phase 3, we administered 28-item K and nine-item A pilot questionnaires to 200 purposively recruited DR/DME patients (mean age, 59.0 ± 10.6 years; 59% male). The psychometric properties of DRKA were assessed using Rasch and classical methods. The association between K and A and DR-related Access was assessed using univariable linear regression of mean K/A scores against Access. Results: Following Rasch-guided amendments, the final 22-item K and nine-item A scales demonstrated adequate psychometric properties, although precision remained borderline. The scales displayed excellent discriminant validity, with K/A scores increasing as education level increased. Compared to those with low scores, those with high K/A scores were more likely to report better access to DR-related information, with K scores of 0.99 ± 0.86 for no difficulty; 0.79 ± 1.05 for a little difficulty; and 0.24 ± 0.85 for moderate or worse difficulty (P < 0.001). Conclusions: The psychometrically robust 31-item DRKA questionnaire can measure DR- and DME-related knowledge and attitudes. Translational Relevance: The DRKA questionnaire may be useful for interventions to improve DR-related knowledge and attitudes and, in turn, optimize health behaviors and health literacy.

Differential Impact of Unilateral and Bilateral Classifications of Diabetic Retinopathy and Diabetic Macular Edema on Vision-Related Quality of Life.

PURPOSE: To evaluate and compare the impact of unilateral better-eye and bilateral categorizations of diabetic retinopathy (DR) and diabetic macular edema (DME) on vision-related quality of life (VRQoL) in individuals with type 2 diabetes (T2DM). METHODS: We recruited 390 subjects (116 females; age range, 22-78 years) of Malay, Indian, and Chinese ethnicities from the Singapore Diabetes Management Project (S-DMP), a cross-sectional clinic-based study conducted from 2010 to 2013. Diabetic retinopathy and DME were graded using the Modified Airlie House and American Academy of Ophthalmology classification systems, respectively. Subjects were categorized, using unilateral better-eye classifications, into no DR (n = 189), any DR only (n = 164), and any DME (n = 37); and with bilateral classifications into no DR (n = 144), DR/DME in one eye only (n = 45), DR in one eye and DR/DME in the other (n = 164), and DME in both eyes (n = 37). Vision-related quality of life was assessed using the composite Rasch-transformed score of the Impact of Visual Impairment (IVI) questionnaire. RESULTS: For unilateral better-eye classifications, multivariable linear models revealed a 9% reduction in VRQoL for any DR (ß [95% confidence interval (CI)], -0.44 [-0.86, -0.03]) and a 17% reduction for any DME (-0.81 [-1.53, -0.08]) compared to individuals with no DR/DME. Bilateral categorizations revealed significant decrements in VRQoL that occurred only when both eyes had either DR or DME (11%), which worsened when both eyes were affected by DME (22%). CONCLUSIONS: Our results suggest that interventions to prevent the onset of DR and/or DME in the second eye are strongly recommended to significantly reduce the bilateral impact of these conditions on VRQoL.