The impact of diabetic retinopathy: understanding the patient’s perspective E K Fenwick, 1 K Pesudovs, 2 G Rees, 1 M Dirani, 1 R Kawasaki, 1 T Y Wong, 1,3 E L Lamoureux 1,3 ABSTRACT Understanding the impact of a condition from the patient’s perspective is important, and different types of patient-reported outcomes or instruments are available to help with this. This review article summarises the current evidence on the impact of diabetic retinopathy (DR) and its associated vision impairment on patient- reported outcomes. We have included research that has used a range of outcome measures to assess the impact of DR on generic health-related quality of life, utility, vision-functioning and vision-specific quality of life. This review also offers clarification on frequently misused psychometric terminologies to help clinicians and researchers better understand the literature associated with patient-reported outcome research. Overall, the evidence suggests that DR, particularly in its vision- threatening stages, has a substantial, negative impact on the patient. However, our understanding of the impact of DR is currently restricted due to limitations inherent in currently available patient-reported outcome measures. We conclude by discussing potential directions for future research in this area, such as item banking and computer adaptive testing. INTRODUCTION Diabetic retinopathy (DR) is a serious microvas- cular complication of diabetes. 1 Nearly all patients with type 1 diabetes and more 60% of those with type 2 diabetes will develop some degree of DR after 20 years of diabetes. 23 In its non-proliferative stages, DR is mostly asymptomatic but may cause significant and disabling vision loss once it prog- resses to severe non-proliferative DR (NPDR) and proliferative DR (PDR) stages. Furthermore, clini- cally significant diabetic macular oedema (DME), which causes centralised vision loss, can occur at any stage. 34 Vision impairment from DR and DME places a considerable burden on patients’ quality of life (QoL). 5e8 The stages of DR are classified according to the presence and extent of well-defined clinical signs. The advanced stages affect visual performance in a number of ways, including visual acuity, depth perception, colour and contrast sensitivity, and visual field. 9 To complement objective visual acuity information, it is now accepted that an assessment of the impact of DR on patients’ QoL using a patient-reported outcome (PRO) is important for clinical trials, interventions or outcomes research. 10e12 While there are a number of tools that have been developed to measure the impact of DR-related vision loss on health-related QoL, 13 our understanding remains limited. 14 The aim of this paper is to provide a critical review of the current research investigating the impact of DR on PROs. We focus on vision-related QoL, a complex concept that encompasses func- tional ability, symptoms, emotional well-being, social relationships, concerns and convenience as they are affected by vision. 15 However, as other parameters are often used, sometimes mistakenly, to characterise vision-related QoL, we also include studies that have assessed the impact of DR using generic health-related QoL questionnaires, utilities and visual functioning questionnaires. Table 1 summarises the different characteristics of these PROs. 34 This review also offers a critical appraisal of the outcome measures used by researchers to assess QoL, and informs the readers about future directions to overcome these limitations, such as the third generational outcome measures ‘item banking’ and ‘computer adaptive testing’ (CAT). METHODS Our literature search included the Pubmed, ISI Web of Science and Embase databases and no date restriction was applied. Articles in languages other than English were not considered. Search terms included variations of keywords for diabetic reti- nopathy; diabetic macular (o)edema; diabetic vision loss; vision impairment; quality of life; functioning; and impact. Names of specific questionnaires or utility measures were also used in conjunction with the other search terms. Additional papers were obtained from the reference lists of relevant papers. Papers not relevant for the purpose of this review were excluded by reviewing the title and abstract. IMPACT OF DR ON PROS The following sections review the published find- ings on the impact of DR on PROs according to the type of instrument used. Table 2 provides a summary of the search findings. Generic health-related PROs Several studies have used the short-form (SF-12, -20 and -36) questionnaire series 28e30 to assess the impact of DR on health-related QoL and results have been inconsistent. 35 38 For example, Davidov and associates found a significant reduction in physical and mental well-being due to DR, DME and visual acuity impairment. 36 Similarly, Clarke and associates found that all health domains were associated with poorer levels of visual acuity, with a linear relationship between worsening visual acuity and declining scores for each domain. 37 Another study found that severe vision loss or 1 Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia 2 NH&MRC Centre for Clinical Eye Research, Discipline of Optometry and Vision Science, Flinders University and Flinders Medical Centre, Australia 3 Singapore Eye Research Institute, Singapore National Eye Centre, Singapore Correspondence to A/Professor Ecosse Lamoureux, Centre for Eye Research Australia, University of Melbourne, 32 Gisborne St, East Melbourne, VIC 3002, Australia; ecosse@unimelb.edu.au Accepted 29 August 2010 Published Online First 12 October 2010 774 Br J Ophthalmol 2011;95:774e782. doi:10.1136/bjo.2010.191312 Review group.bmj.com on May 30, 2012 - Published by bjo.bmj.com Downloaded from