Retinopathy as an independent predictor of all-cause mortality in individuals with type 2 diabetes

Abstract

Aims: To assess whether the presence and grade of diabetic retinopathy (DR) predict all-cause mortality, independent of risk factors for cardiovascular disease (CVD) and other complications, including diabetes-related kidney disease (DKD) and CVD, in individuals with type 2 diabetes mellitus.

Methods: Prospective cohort study that enroled 15,773 patients in 19 Italian centers in 2006-2008. DR ascertained by fundoscopy, DKD by albuminuria and estimated glomerular filtration rate, and prior CVD by hospital discharge records. All-cause mortality retrieved for 15,656 patients on 31 October 2015.

Results: The adjusted risk of death was increased in patients with any DR (hazard ratio, 1.136 [95% confidence interval, 1.054;1.224] P < 0.0001), advanced DR, including severe non-proliferative and proliferative DR and diabetic macula edema (1.213 [1.097;1.340] P < 0.0001), and especially proliferative DR alone (1.381 [1.207;1.580] P < 0.0001), compared with those without DR. The impact of DR was more evident in patients without than in those with DKD or CVD. Mortality risk was increased in participants with DR alone, though much less than in those with DKD or CVD alone and particularly in those with both DR and DKD or CVD. DR grade was related to mortality in individuals without DKD or CVD, whereas it conferred no additional risk to those with albuminuric or nonalbuminuric DKD or established CVD.

Conclusions: In patients with type 2 diabetes mellitus, the excess mortality risk conferred by DR is relatively small and higher in those without DKD and CVD, suggesting that it may be mediated by the concurrent presence of these complications, even at a subclinical level.

Keywords: All-cause mortality; Cardiovascular disease; Diabetes-related kidney disease; Diabetic retinopathy; Type 2 diabetes.