Can the retinal screening interval be safely increased to 2 years for type 2 diabetic patients without retinopathy?

Abstract

Objective: In the U.K., people with diabetes are typically screened for retinopathy annually. However, diabetic retinopathy sometimes has a slow progression rate. We developed a simulation model to predict the likely impact of screening patients with type 2 diabetes, who have not been diagnosed with diabetic retinopathy, every 2 years rather than annually. We aimed to assess whether or not such a policy would increase the proportion of patients who developed retinopathy-mediated vision loss compared with the current policy, along with the potential cost savings that could be achieved.

Research design and methods: We developed a model that simulates the progression of retinopathy in type 2 diabetic patients, and the screening of these patients, to predict rates of retinopathy-mediated vision loss. We populated the model with data obtained from a National Health Service Foundation Trust. We generated comparative 15-year forecasts to assess the differences between the current and proposed screening policies. RESULTS The simulation model predicts that implementing a 2-year screening interval for type 2 diabetic patients without evidence of diabetic retinopathy does not increase their risk of vision loss. Furthermore, we predict that this policy could reduce screening costs by ~25%.

Conclusions: Screening people with type 2 diabetes, who have not yet developed retinopathy, every 2 years, rather than annually, is a safe and cost-effective strategy. Our findings support those of other studies, and we therefore recommend a review of the current National Institute for Health and Clinical Excellence (NICE) guidelines for diabetic retinopathy screening implemented in the U.K.

Figure 1

Patient-level processes in ReSS model. This flowchart summarizes the process steps that patients in the model follow.

Figure 2

Proportion of type 2 diabetic patients who lost their vision. The figure shows the total proportion of type 2 diabetic patients in the model who lost their vision within the simulated period of 15 years. Results are shown for both the current screening policy (2S) and the proposed three-tier screening policy (3S). Results are averaged over 10 replications of the simulation.

Figure 3

Estimated cost of screening over 15 years. The figure compares the estimated total type 2 diabetic patient screening costs over 15 years of the current screening policy (2S) with the proposed three-tier screening policy (3S). Results are averaged over 10 replications of the simulation.