Diabetic Retinopathy May Predict Greater Risk of COVID-19 Severity

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Risk of intubation for COVID-19 in very sick hospitalized patients was increased over fivefold in those with diabetic retinopathy compared to those without, in a small single-center study from the UK.

Importantly, the risk of intubation was independent of conventional risk factors for poor COVID-19 outcomes.

"People with pre-existing diabetes-related vascular damage, such as retinopathy, might be predisposed to a more severe form of COVID-19 requiring ventilation in the intensive therapy unit," said lead investigator Janaka Karalliedde, MBBS, PhD.

Karalliedde and his colleagues note that this is "the first description of diabetic retinopathy as a potential risk factor for poor COVID-19 outcomes."

"For this reason, looking for the presence or history of retinopathy or other vascular complications of diabetes may help health care professionals identify patients at high risk of severe COVID-19," added Karalliedde, of Guy's and St Thomas' NHS Foundation Trust, London, UK.

The study was published online in Diabetes Research and Clinical Practice.

Pre-existing Diabetic Retinopathy and COVID-19 Outcomes

The prevalence of diabetic retinopathy is thought to be around 55% in people with type 1 diabetes and 30% in people with type 2 diabetes, on average.

Karalliedde is part of a research group at King's College London that has been focused on how vascular disease may predispose to more severe COVID-19.

"COVID-19 affects the blood vessels all over the body," he said, so they wondered whether having pre-existing retinopathy "would predispose to a severe manifestation of COVID-19."

The observational study included 187 patients with diabetes (179 patients with type 2 diabetes and eight patients with type 1 diabetes) hospitalized with COVID-19 at Guy's and St Thomas' NHS Foundation Trust between March 12 to April 7 (the peak of the first wave of the pandemic in the UK).

"It was an ethnically diverse population who were very sick and provides a clinical observation of real life," Karalliedde said.

Nearly half of patients were African Caribbean (44%), 39% were White, and 17% were of other ethnicities, including 8% who were Asian. The mean age of the cohort was 68 years (range, 22-97 years), and 60% were men.

Diabetic retinopathy was reported in 67 (36%) patients, of whom 80% had background retinopathy and 20% had more advanced retinopathy.

They then looked at whether the presence of retinopathy was associated with a more severe manifestation of COVID-19 as defined by the need for tracheal intubation.

Of the 187 patients, 26% were intubated and 45% of these patients had diabetic retinopathy.

The analysis showed those with diabetic retinopathy had an over fivefold increased risk for intubation (OR, 5.81; 95% CI, 1.37 - 24.66).

IOf the entire cohort, 32% of patients died, although no association was observed between retinopathy and mortality.

"A greater number of diabetes patients with COVID-19 ended up on the intensive therapy unit. Upon multivariate analysis, we found retinopathy was independently associated with ending up on the intensive therapy unit," stressed Karalliedde.

However, they note that "Due to the cross-sectional design of our study, we cannot prove causality [between retinopathy and intubation]."

"Further studies are required to understand the mechanisms that explain the associations between retinopathy and other indices of microangiopathy with severe COVID-19."

Diabetes Res Clin Pract. Published online November 2, 2020. Full text

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