Patients with high blood pressure are at an increased risk of dying from COVID-19, particularly if they are not taking any medication to control the condition, a new study involving Irish researchers has found.

High blood pressure, also known as hypertension, is a major cause of heart attack and stroke. However, it rarely carries any signs or symptoms. In fact, a person can look and feel well even if they have it.

Almost one million people in Ireland have high blood pressure, including around two-thirds of people over the age of 50. However, as many as half of these may not be aware they have the condition.

The only way to know if you have high blood pressure is to have it checked by a health professional, such as a GP or pharmacist.

This latest study involved researchers from NUI Galway and China. They analysed data from 2,866 patients who had been admitted to Huo Shen Shan Hospital in Wuhan, China, between February 5 and March 15. This hospital was opened on February 5 for the sole purpose of treating COVID-19 patients.

Among the 2,866 patients, 29.5% had a medical history of high blood pressure.

The researchers found that those with high blood pressure had a two-fold increased risk of dying from COVID-19, even after other factors were taken into account, such as age and other medical conditions.

Furthermore, among those patients with high blood pressure, those who were not taking medication for the condition had a 2.17-fold increased risk of dying from the virus compared to those who did take medication.

"It is important that patients with high blood pressure realise that they are at increased risk of dying from COVID-19. They should take good care of themselves during this pandemic and they need more attention if they are infected with the coronavirus.

"In addition, 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," commented one of the lead researchers, Prof Fei Li of Xijing Hospital in China.

Meanwhile, the researchers also pooled this data with data involving almost 2,300 patients who were taking part in three other studies. They found that patients treated with drugs to control blood pressure levels by targeting the renin-angiotensin-aldosterone system (RAAS), had a lower risk of death than those treated with other drugs.

RAAS inhibiting drugs include angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). Non-RAAS inhibiting drugs used for treating high blood pressure include beta blockers, calcium channel blockers (CCBs) and diuretics.

However, the researchers acknowledged that the number of patients in this particular analysis was small, so the findings could be due to chance.

"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. Therefore, we suggest that patients should not discontinue or change their usual antihypertensive treatment unless instructed by a physician," Prof Li said.

As fewer cases of COVID-19 are now being diagnosed in China, a randomised clinical trial is to be run in NUI Galway by Professors J. William McEvoy and Patrick Serruys, who are co-authors of this study.

"There are three remaining questions, and we hope our clinical trial in Ireland will answer the first two: what kind of medication should be given to COVID-19 patients with hypertension - RAAS inhibitors or non-RAAS inhibitors - and could these medications mitigate the risk of dying in these patients?

"As for the last question, a recent population-based study in the New England Journal of Medicine has suggested that antihypertensive medications, such as ACE inhibitors and ARBs are not associated with an increased risk of testing positive for COVID-19," Prof Serruys commented.

Details of these findings are published in the European Heart Journal.