This US retrospective cohort study evaluated the relationship between the severity of diabetic retinopathy (DR) in patients with type 2 diabetes mellitus and the risk of developing cerebrovascular accident (CVA), myocardial infarction (MI), congestive heart failure (CHF), and all-cause mortality.
Study design
Investigators reviewed the records of 77,376 patients with type 2 diabetes mellitus who underwent DR screening via fundus photography. The relationship between retinopathy status and the 5-year risk of first-time CVA, MI, CHF, and all-cause mortality was investigated using multivariate Cox proportional hazards regressions that controlled for factors such as age, gender, race/ethnicity, hemoglobin A1c, lipid levels, blood pressure, and estimated glomerular filtration rate. The primary outcome was first-time CVA, MI, CHF, and all-cause mortality over a 5-year period.
Outcomes
Diabetic retinopathy was significantly associated with all outcomes, with the risk increasing with greater DR severity. Patients with minimal nonproliferative diabetic retinopathy (NPDR) had a higher risk of CVA (hazard ratio [HR] 1.31), MI (HR 1.30), CHF (HR 1.29), and death (HR 1.15) than patients without retinopathy. Similarly, patients with moderate-to-severe NPDR had a higher risk of each outcome (CVA: HR 1.56; MI: HR 1.92; CHF: HR 1.90; death: HR 1.55; 95% CI), as did patients with proliferative DR. Factors contributing to greater risk of CVA, MI, CHF, and death included increasing age, higher hemoglobin A1c values, and a history of hypertension.
Limitations
One limitation of the study was that patients were enrolled from a screening program; therefore, it is likely that fewer patients with more severe forms of DR were included. Any confounders between type 2 diabetes mellitus and vascular disease, which could have influenced the results, may also have gone unidentified.
Clinical significance
The presence of DR is significantly associated with future risk of developing cardiovascular outcomes and death, with greater DR severity linked with a heightened risk for each outcome. Data from ophthalmologist visits for DR can provide helpful information for the management of diabetes and vascular disease.