Associations between attainment of incentivised primary care indicators and incident diabetic retinopathy in England: a population-based historical cohort study.

Background: The associations between England's incentivised primary care-based diabetes prevention activities and hard clinical endpoints remain unclear. We aimed to examine the associations between attainment of primary care indicators and incident diabetic retinopathy (DR) among people with type 2 diabetes.

Methods: A historical cohort (n = 60,094) of people aged ≥ 18 years with type 2 diabetes and no DR at baseline was obtained from the UK Clinical Practice Research Datalink (CPRD). Exposures included attainment of the Quality and Outcomes Framework (QOF) HbA1c (≤ 7.5% or 59 mmol/mol), blood pressure (≤ 140/80 mmHg), and cholesterol (≤ 5 mmol/L) indicators, and number of National Diabetes Audit (NDA) care processes completed (categorised as 0-3, 4-6, or 7-9), in 2010-2011. Outcomes were time to development of DR and sight-threatening diabetic retinopathy (STDR). Nearest neighbour propensity score matching was undertaken and Cox proportional hazards models then fitted using the matched samples. Concordance statistics were calculated for each model.

Results: 8263 DR and 832 STDR diagnoses were observed over mean follow-up periods of 3.5 (SD 2.1) and 3.8 (SD 2.0) years, respectively. HbA1c and blood pressure (BP) indicator attainment were associated with lower rates of DR (adjusted hazard ratios (aHRs) 0.94 (95% CI 0.89-0.99) and 0.87 (0.83-0.92), respectively), whereas cholesterol indicator attainment was not (aHR 1.03 (0.97-1.10)). All QOF indicators were associated with lower rates of STDR (aHRs 0.74 (0.62-0.87) for HbA1c, 0.78 (0.67-0.91) for BP, and 0.82 (0.67-0.99) for cholesterol). Completion of 7-9 vs. 0-3 NDA processes was associated with fewer STDR diagnoses (aHR 0.72 (0.55-0.94)).

Conclusions: Attainment of key primary care indicators is associated with lower incidence of DR and STDR among patients with type 2 diabetes in England.