Validation of a novel diabetic retinopathy utility index using discrete choice experiments

Eva K Fenwick; Nick Bansback; Alfred Tau Liang Gan; Julie Ratcliffe; Leonie Burgess; Tien Yin Wong; Ecosse Luc Lamoureux

doi:10.1136/bjophthalmol-2019-313899

Validation of a novel diabetic retinopathy utility index using discrete choice experiments

Br J Ophthalmol. 2020 Feb;104(2):188-193. doi: 10.1136/bjophthalmol-2019-313899. Epub 2019 May 16.

Authors

Eva K Fenwick^{1

2

3}, Nick Bansback⁴, Alfred Tau Liang Gan¹, Julie Ratcliffe⁵, Leonie Burgess⁶, Tien Yin Wong^{1

3

7}, Ecosse Luc Lamoureux^{8

2

3}

Affiliations

¹ Health Services Research Unit, Singapore Eye Research Institute, Singapore, Singapore.
² Ophthalmology, University of Melbourne, Melbourne, Victoria, Australia.
³ Health Services and Systems Research, Duke-NUS Medical School, Singapore, Singapore.
⁴ School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada.
⁵ Institute for Choice, Business School, University of South Australia, Adelaide, South Australia, Australia.
⁶ Sax Institute, Haymarket, Ultimo, Australia.
⁷ Singapore National Eye Centre, Singapore, Singapore.
⁸ Health Services Research Unit, Singapore Eye Research Institute, Singapore, Singapore ecosse@unimelb.edu.au.

PMID: 31097442
DOI: 10.1136/bjophthalmol-2019-313899

Abstract

Background/aims: To validate a preference-based Diabetic Retinopathy Utility Index (DRU-I) using discrete choice experiment (DCE) methods and assess disutilities associated with vision-threatening DR (VTDR: severe non-proliferative DR, proliferative DR and clinically significant macular oedema) and associated vision impairment.

Methods: The DRU-I comprises five quality-of-life dimensions, including Visual symptoms, Activity limitation/mobility, Lighting and glare, Socio-emotional well-being and Inconvenience, each rated as no, some, or a lot of difficulty. The DRU-I was developed using a DCE comprising six blocks of nine choice sets which, alongside the EuroQoL-5D (EQ-5D-3L) and Vision and Quality of Life (VisQoL) utility instruments, were interviewer-administered to participants. To ensure the DRU-I was sensitive to severe disease, we oversampled patients with VTDR. Data were analysed using conditional logit regression.

Results: Of the 220 participants (mean±SD age 60.1±11.3 years; 70.9% men), 57 (29.1%) and 139 (70.9%) had non-VTDR and VTDR, respectively, while 157 (71.4%), 20 (9.4%) and 37 (17.3%) had no, mild or moderate/severe vision impairment, respectively. Regression coefficients for all dimensions were ordered as expected, with worsening levels in each dimension being less preferred (theoretical validity). DRU-I utilities decreased as DR severity (non-VTDR=0.87; VTDR=0.80; p=0.021) and better eye vision impairment (none=0.84; mild=0.78; moderate/severe=0.72; p=0.012) increased. DRU-I utilities had low (r=0.39) and moderate (r=0.58) correlation with EQ-5D and VisQoL utilities, respectively (convergent validity).

Discussion: The DRU-I can estimate utilities associated with vision-threatening DR and associated vision impairment. It has the potential to assess the cost-effectiveness of DR interventions from a patient perspective and inform policies on resource allocation relating to DR.

Keywords: diabetic retinopathy; discrete choice experiment; health economics; quality of life; utility; vision impairment.

Publication types

Research Support, Non-U.S. Gov't
Validation Study

MeSH terms

Activities of Daily Living
Adult
Aged
Cost of Illness
Cross-Sectional Studies
Diabetic Retinopathy* / complications
Diabetic Retinopathy* / diagnosis
Diabetic Retinopathy* / psychology
Female
Health Status
Humans
Logistic Models
Male
Middle Aged
Outcome Assessment, Health Care
Quality of Life
Severity of Illness Index*
Surveys and Questionnaires / standards*
Vision Disorders* / diagnosis
Vision Disorders* / etiology
Vision Disorders* / psychology