Evaluation of a new model of care for people with complications of diabetic retinopathy: the EMERALD Study

Objectives: The increasing diabetes prevalence and advent of new treatments for its major visual-threatening complications (diabetic macular edema [DME] and proliferative diabetic retinopathy [PDR]), which require frequent and life-long follow-up, have markedly increased hospital demands. Resulting delays in the evaluation/treatment of patients are leading to sight loss. Strategies to increase capacity of medical retina clinics are urgently needed. EMERALD tested diagnostic accuracy, acceptability and costs of a new health care pathway for people with previously treated DME/PDR. Design: Prospective, multicentric, case-referent, cross-sectional, diagnostic accuracy study, undertaken in 13 hospitals in the United Kingdom. Participants: Adults with type 1 or 2 diabetes and previously successfully treated DME/PDR who, at the time of enrolment, had active or inactive disease. Methods: A new health care pathway entailing multimodal imaging (spectral domain optical coherence tomography [SD-OCT] for DME, and 7-field Early Treatment Diabetic Retinopathy Study [ETDRS] and ultra-wide-field fundus images [UWF] for PDR) interpreted by trained non-medical staff (ophthalmic graders) to detect re-activation of disease was compared with the current standard care (ophthalmologists face-to-face examination). Main Outcome Measures: Primary outcome: sensitivity of the new pathway. Secondary outcomes: specificity; agreement between pathways; costs; acceptability; proportions requiring subsequent ophthalmologist assessment, unable to undergo imaging, with inadequate images/indeterminate findings. Results: The new pathway had sensitivity of 97% (95% confidence interval [CI] 92-99%) and specificity of 31% (95% CI 23-40%) to detect DME. For PDR, sensitivity and specificity using 7-field ETDRS (85%, 95% CI 77-91%; 48%; 95% CI 41-56%, respectively) or UWF (83%, 95% CI 75-89%; 54%; 95% CI 46-61%, respectively) were comparable. For detection of high risk PDR sensitivity and specificity were higher when using UWF images (87%, 95% CI 78-93%; 49% 95% CI 42-56%, respectively for UWF, versus 80%, 95% CI 69-88%; 40% CI 34-47%, respectively, for 7-field ETDRS). Participants preferred ophthalmologist’s assessments; in their absence, wished immediate feedback by graders, maintaining periodic ophthalmologist evaluations. When compared with the current standard care, the new pathway could save £1,390/100 DME visits and between £461-£1,189/100 PDR visits. Conclusion: The new ophthalmic grader pathway has acceptable sensitivity and would release resources. Users’ suggestions should guide implementation.