A study of strokes among coronavirus disease patients in India has revealed an unusually large proportion of patients without the traditional risk factors such as high blood pressure and also pointed to greater residual disability levels than in other stroke survivors.

The study by neurologists in Bangalore analysed the features and outcomes of strokes in 62 Covid-19 patients in 13 hospitals between June and August this year and compared them with those of 111 stroke patients they had treated last year during the same months.

Sixteen (26 per cent) of the 62 Covid-19 stroke patients did not have any history of conventional risk factors for stroke such as high blood pressure, diabetes, or cardiovascular disease compared with only 5 (4.5 per cent) of 111 patients.

“This points to a five-fold increased stroke risk for patients who otherwise had no conventional risk factor for stroke,” said John Mathew, professor and head of neurology at the St John’s National Academy of Health Sciences, Bangalore, who coordinated the study.

“Our findings bolster evidence for the idea that Covid-19 itself is a risk factor for stroke,” he said.

The stroke severity was also high among Covid-19 patients. None of the 62 patients had a minor stroke, while 60 (54 per cent) of the 111 stroke patients treated last year had minor stroke. And 11 (17 per cent) of the Covid-19 patients had a severe stroke, compared with only one of the 111 patients last year.

The study, published in the International Journal of Stroke, also found that 37 (59 per cent) of the 62 Covid-19 stroke patients had moderate to severe residual neurological disability at the time of their discharge. Fewer proportions of the 111 patients had moderate to severe residual disabilities.

Thirteen (21 per cent) of Covid-19 stroke patients died, while none of the 111 patients had died.

The findings are in line with international studies that have noted that strokes associated with Covid-19 are likely to be more severe with worse outcomes and higher mortality than non-Covid-19 strokes.

Neuroscientists at the University of Cambridge in the UK had last week estimated that about 14 in every 1,000 Covid-19 patients admitted to hospital experience a stroke, a rate that is higher than the incidence of stroke among older patients and other patients with severe infections.

“Even though the incidence of stroke among Covid-19 patients is relatively low, the scale of the pandemic means many thousands of people could be potentially affected worldwide,” Hugh Markus, professor and neurologist at the University of Cambridge, said in a media release.

Neurologists across India are concerned that as the country’s Covid-19 epidemic grows, the number of patients susceptible to stroke will also increase.

The Bangalore study which found a five-fold increased risk of stroke in patients without any underlying health disorders such as hypertension or diabetes suggests that Covid-19 itself is a trigger for stroke.