Diabetic retinopathy prognostic of poor COVID-19 outcomes among diabetic patients

Among diabetes mellitus patients with COVID-19, the presence of diabetic retinopathy (DR) is independently associated with poor COVID-19 prognosis, as shown in a study.

Researchers searched multiple online databases for noninterventional observational studies that evaluated DR as a prognostic factor (independently or with other microvascular diseases) for COVID-19 among infected patients with diabetes. The search yielded a total of 376 studies, of which eight were included in the narrative synthesis.

Of the studies, seven were from western Europe and one was from China. Seven studies were conducted in the pandemic’s first wave (March 2020 to July 2020) and one in the second wave (September 2020 to December 2020). Age, ethnicity, and sex were similar across the studies. Only one study included patients with type 1 diabetes; the rest involved patients with type 2 diabetes only.

Due to the considerable heterogeneity between studies, a meta-analysis could not be performed. The major risks of bias were in outcome definition and prognostic factor identification. Furthermore, variability between studies limited comparability.

Three studies reported significant positive associations between DR and poor COVID-19 outcomes. The study with the highest quality showed that referable-grade DR was associated with an elevated risk of the combined outcome of fatal or critical care unit-treated COVID-19 (odds ratio, 1.672, 95 percent confidence interval, 1.38–2.03).

Four studies indirectly reported positive associations between microvascular disease and poorer prognosis.

More studies that apply standardized methodology are needed in order to establish the prognostic value of DR with greater confidence.