Two-year recall for people with no diabetic retinopathy: a multiethnic population-based retrospective cohort study using real-world data to quantify the effect

Background/Aims: The English Diabetic Eye Screening Programme (DESP) offers people living with diabetes (PLD) annual screening. Less frequent screening has been advocated among PLD without diabetic retinopathy (DR), but evidence for each ethnic group is limited. We examined the potential effect of biennial vs annual screening on the detection of sight-threatening diabetic retinopathy (STDR) and proliferative diabetic retinopathy (PDR) among PLD without DR from a large urban-multi-ethnic English DESP. Methods: PLD in North-East London DESP (Jan-2012 to Dec-2021) with no DR on two prior consecutive screening visits with up to eight years of follow-up were examined. Annual STDR and PDR incidence rates, overall, and by ethnicity were quantified. Delays in identification of STDR and PDR events had 2-year screening intervals been used were determined. Findings: Among 82,782 PLD (37% white, 36% South Asian, and 16% black people), there were 1,788 incident STDR cases over mean 4.3 (SD 2.4) years (STDR rate 0.51, 95%CI 0.47-0.55 per 100-person-years). STDR incidence rates per 100-person-years by ethnicity were 0.55 (95% CI 0.48-0.62) for South Asian, 0.34 (0.29-0.40) for white, and 0.77 (0.65-0.90) for black people. Biennial screening would have delayed diagnosis by 1-year for 56.3% (1,007/1,788) with STDR and 43.6% (45/103) with PDR. Standardised cumulative rates of delayed STDR per-100,000 for each ethnic group were 1904 (95%CI 1683-2154) for black, 1276 (1153-1412), and 844 (745-955) for white people. Interpretation: Biennial screening would have delayed detection of some STDR and PDR by one-year especially among those of black ethnic origin, leading to healthcare inequalities.