Individualised risk assessment for diabetic retinopathy and optimisation of screening intervals: a scientific approach to reducing healthcare costs

Abstract

ObjectiveTo validate a mathematical algorithm that calculates risk of diabetic retinopathy progression in a diabetic population with UK staging (R0–3; M1) of diabetic retinopathy. To establish the utility of the algorithm to reduce screening frequency in this cohort, while maintaining safety standards.Research design and methodsThe cohort of 9690 diabetic individuals in England, followed for 2 years. The algorithms calculated individual risk for development of preproliferative retinopathy (R2), active proliferative retinopathy (R3A) and diabetic maculopathy (M1) based on clinical data. Screening intervals were determined such that the increase in risk of developing certain stages of retinopathy between screenings was the same for all patients and identical to mean risk in fixed annual screening. Receiver operating characteristic curves were drawn and area under the curve calculated to estimate the prediction capability.ResultsThe algorithm predicts the occurrence of the given diabetic retinopathy stages with area under the curve =80% for patients with type II diabetes (CI 0.78 to 0.81). Of the cohort 64% is at less than 5% risk of progression to R2, R3A or M1 within 2 years. By applying a 2 year ceiling to the screening interval, patients with type II diabetes are screened on average every 20 months, which is a 40% reduction in frequency compared with annual screening.ConclusionsThe algorithm reliably identifies patients at high risk of developing advanced stages of diabetic retinopathy, including preproliferative R2, active proliferative R3A and maculopathy M1. Majority of patients have less than 5% risk of progression between stages within a year and a small high-risk group is identified. Screening visit frequency and presumably costs in a diabetic retinopathy screening system can be reduced by 40% by using a 2 year ceiling. Individualised risk assessment with 2 year ceiling on screening intervals may be a pragmatic next step in diabetic retinopathy screening in UK, in that safety is maximised and cost reduced by about 40%.

The English National Screening Programme for diabetic retinopathy 2003–2016

“…Extensive work has been done in the area [37–40] of extended screening intervals for those at low risk. The UK National Screening Committee agreed at their committee on 19 November 2015 and published their recommendation in January 2016 that:

For people with diabetes at low risk of sight loss, the interval between screening tests should change from 1 to 2 years.

The current 1 -year interval should remain unchanged for the remaining people at high risk of sight loss.

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Evidence‐based Danish guidelines for screening of diabetic retinopathy

“…It has been demonstrated that in comparison with fixed screening intervals, flexible and individualized screening intervals can be used to extend the screening intervals almost three times (Mehlsen et al 2012) and reduce the number of screening episodes by 40% (Aspelund et al 2011;Lund et al 2016). These benefits are in particular based upon an extended screening interval of more than 12 months in patients with no or minimal DR (Kristinsson et al 1995;Hansson-Lundblad et al 1997;Olafsdottir & Stefansson 2007;Misra et al 2009;Agardh & Tababat-Khani 2011;Echouffo-Tcheugui et al 2013;Taylor-Phillips et al 2016).…”

Diabetic Retinopathy in Italy: Epidemiology Data and Telemedicine Screening Programs

“…Biennial screening showed long safety record in Iceland and Sweden [42, 43]. Moreover, adopting biennial screening approach, a reduction in approximately 25% of screening costs can be obtained without increased risk to the patient [44].…”