Patients with high blood pressure who are not taking medication to control the condition may be at a greater risk of dying from novel coronavirus infection, according to a review of studies which says drugs treating the underlying disease may offer protection in some COVID-19 patients.
The research, published in the European Heart Journal, noted that patients with elevated blood pressure have a two-fold increased risk of dying from the novel coronavirus infection, compared to those without the underlying disease.
In the study, scientists, including those from Xijing Hospital in China, assessed data from 2,866 COVID-19 patients who were admitted to Huo Shen Shan hospital in China, between February 5 and March 15.
They said nearly 30 per cent of these patients (850) had a medical history of high blood pressure, also known as hypertension.
According to the study, led by Fei Li and Ling Tao from Xijing Hospital, 34 out of 850 hypertensive patients (4 per cent) with coronavirus died compared to 22 out of 2027 patients without hypertension (1.1 per cent).
The scientists said this was a 2.12-fold increased risk of dying from the disease after they adjusted for several health-related factors that could affect the results, such as age, sex, and other medical conditions.
Among the patients with hypertension who were not taking medication for the condition, the study said 11 out 140 people (nearly 8 per cent) died from coronavirus, compared to 23 out of 710 (3.2 per cent) of those who were taking medication -- a 2.17-fold increased risk after adjusting for confounding factors.
Analysing data from nearly 2,300 patients in three other studies, the researchers probed into the death rates in patients being treated with drugs to control blood pressure levels which targeted the renin-angiotensin-aldosterone system (RAAS) of the human body.
These drugs, they said, included angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs).
The scientists also assessed the performance of other, non-RAAS inhibiting drugs used for treating high blood pressure such as beta blockers, calcium channel blockers (CCBs), or diuretics.
In their analysis, the researchers found a lower risk of death among the 183 patients treated with RAAS inhibitors than in 527 patients treated with other drugs.
However, the scientists say this result should be treated with caution as the number of patients in this analysis was small, and so it could be due to chance.
"It is important that patients with high blood pressure realise that they are at increased risk of dying from COVID-19," Li said.
"They should take good care of themselves during this pandemic and they need more attention if they are infected with the coronavirus," he added.
In addition, the scientists noted that there were 140 patients admitted to hospital with COVID-19 who had discontinued their anti-hypertensive treatment due to various reasons.
"We found that this was associated with a greater risk of dying from the coronavirus," Li said.
"In contrast to our initial hypothesis, we found that RAAS inhibitors, such as ACE inhibitors or angiotensin receptor blockers, were not linked to an increased risk of dying from COVID-19 and, in fact, may be protective," the scientists said.
They suggested that patients should not discontinue or change their usual antihypertensive treatment unless instructed by a physician.
Since the assessed study looked at data from observations in the hospital, and was not based on a randomised controlled clinical trial, the researchers said it is too early to make clinical recommendations based on these results.
"These data should be interpreted cautiously. However, they support recommendations for the European Society of Cardiology that patients should not discontinue or change their normal, antihypertensive treatment," Tao said.