Anaemia linked to progression of nonproliferative to vision-threatening diabetic retinopathy

Anaemia appears to be involved in the progression from nonproliferative diabetic retinopathy (NPDR) to vision-threatening diabetic retinopathy (VTDR), a recent study has found.

Researchers performed a retrospective cohort study on 69,982 NPDR patients. Anaemia and other oxygen delivery-related comorbidities, such as chronic pulmonary disease, were identified from patient records. The primary study outcome was a new diagnosis of VTDR, proliferative diabetic retinopathy (PDR) or diabetic macular oedema (DME).

Most of the participants (n=57,212; mean age, 61.7±12.9 years; 53.5 percent male) did not progress to VTDR, while the remaining 12,770 (mean age, 60.5±12.1 years; 50.9 percent male) did.

Cox proportional hazards analysis found that after controlling for covariates, mild (hazard ratio [HR], 1.10, 95 percent confidence interval [CI], 1.04–1.16; p<0.001) and moderate/severe (HR, 1.20, 95 percent CI, 1.12–1.29; p<0.001) forms of anaemia were significantly associated with the progression to VTDR.

The same was true for the individual components of VTDR. Mild (HR, 1.29, 95 percent CI, 1.13–1.46; p<0.001) and moderate/severe (HR, 1.43, 95 percent CI, 1.21–1.69; p<0.001) anaemia increased the risk of PDR, as well as of DME (mild: HR, 1.06, 95 percent CI, 1.00–1.13; p<0.001; moderate/severe: HR, 1.14, 95 percent CI, 1.05–1.24; p<0.001).

Other oxygen delivery-related comorbidities also increased the risk of VTDR. This was observed with chronic pulmonary disease (HR, 1.10, 95 percent CI, 1.06–1.14; p<0.001) and a history of blood disorders or cancer (HR, 1.28, 95 percent CI, 1.16–1.40; p<0.001). This effect was driven largely by the effect of the comorbidities on DME risk.