Hypertension is the single largest global contributor to disability-adjusted life years lost.  The majority of the population aged over 60 have hypertension, and appear to be at increased risk from covid-19 infection.  Despite this, and perhaps due to its ubiquity in the older population, current UK Government guidance does not identify people with hypertension as “at risk”, however other bodies such as the British Heart Foundation and the Health Service Executive in Ireland do. [3,4,5] We therefore consider here the question of how hypertension modifies the risks and severity of covid-19, and the implications for hypertension treatment.
The largest case series published to date, from China, found an overall case fatality rate of 2.3 % (1,023 of 44,672 confirmed cases), but 6.0% for people with hypertension.  These data were reported without adjustment for age which is important because both covid-19 case fatality rates and hypertension prevalence increase with age, reaching 8.0% and over 50% respectively for the 70 to 79 year age group.  So, is the association of hypertension with covid-19 anything more than a reflection of the age of hypertensive patients? A new study-level meta-analysis of 2552 confirmed covid-19 patients reported a pooled odds ratio (OR) of 2.49 (95 % confidence interval (CI): 1.98-3.12; 11 studies) for severe disease in the presence of hypertension, with low heterogeneity between studies (I2 = 24 %). The OR for death was similar and weak evidence from meta-regression suggested that hypertension may be a clinical predictor of covid-19 severity in people over 60. 
Are the reported associations of hypertension with severity of covid-19 plausible? Similar findings were reported with previous coronavirus infections, such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS). [8,9] The mechanism for increased risk from covid-19 with hypertension is, however, unclear. The propensity for coronavirus to enter cells through angiotensin-converting enzyme (ACE) 2 has led to suggestions that use of ACE inhibitors and angiotensin II type-I receptor blockers (ARBs) may be implicated.  While gaining much publicity, with attendant worry for patients, this theory is debated; ACE inhibitor and ARB treatment has also been associated with improved outcomes in covid-19.  The National Institute for Health and Care Excellence (NICE) are undertaking a rapid review of this topic, however, no trial evidence demonstrating either benefits or risks from continuing such antihypertensive medications during infection with a coronavirus currently exists.  While it is unknown whether these drugs increase covid-19 severity, the consequences of poor blood pressure control are well documented.  Consequently, the British and Irish Hypertension Society (BIHS), and our European and International partner societies, have issued clear position statements advising against cessation of antihypertensive therapy on the grounds of concern over risks with covid-19 (available at: https://bihsoc.org/bihs-statement-on-acei-arb-and-covid19/). We (the BIHS) disagree with the recent editorial by Aronson & Ferner who suggest that doctors may consider stopping treatment with ACE inhibitors and ARBs in well-controlled patients with mild (Stage 1) hypertension.  The unintended consequences of discontinuing effective treatments for hypertension, without a suitable replacement titrated against blood pressure measurements under direct medical supervision, could put patients at needlessly increased cardiovascular and possibly coronavirus risk. In addition, managing such titration currently, when primary care is prioritising acute illness over routine contacts (including blood pressure checks), makes the proposed strategy impractical and risks further diluting access to care.
So, what can we say to hypertensive patients who may be anxious about taking antihypertensive medication and about their risks from infection during the covid-19 pandemic? The evidence base is limited, so strong recommendations are difficult. However, people with complications of hypertension, such as ischaemic heart disease, are already regarded as being at high risk. It seems reasonable to advise those with poorly controlled hypertension (i.e. blood pressure above guideline targets), particularly if prolonged, to also consider themselves to be at high risk and, therefore, to follow appropriate social distancing advice.  For younger individuals with hypertension, with good control of blood pressure, risks of undiagnosed cardiovascular disease are low, and they could therefore be reassured. We should support all our hypertensive patients in continuing to strive for, and maintain, good blood pressure control by continuing to take their medications as prescribed, and by endeavouring to follow and maintain sensible lifestyle choices, including exercise within the current restrictions. 
Over the coming weeks, large numbers of people are predicted to become affected by covid-19 with potentially profound consequences, however they will also provide data that will help us to understand the true risk from elevated blood pressure on outcomes of the disease. Careful and continuous research is vital for an understanding of the mechanisms underlying any additional risk from hypertension with covid-19, and to determine the best and safest ways to treat those with severe manifestations of disease. Our patients are best served when their treatment is based on available evidence rather than speculation.
Christopher E Clark is a rural GP and Clinical Senior Lecturer in General Practice at the University of Exeter Medical School. He is a Fellow of the British and Irish Hypertension Society.
Sinead TJ McDonagh, Primary Care Research Group, Institute of Health Services Research, University of Exeter Medical School
Richard J McManus, Professor of Primary Care Research, Nuffield Department of Primary Care Health Sciences, University of Oxford
Una Martin, Dean of Birmingham Medical School and President of British and Irish Hypertension Society
on behalf of the British and Irish Hypertension Society
- Global Burden of Disease 2015 Risk Factors Collaborators. Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet 2016;388(10053):1659-724. doi: 10.1016/s0140-6736(16)31679-8 [published Online First: 2016/10/14]
- Kearney PM, Whelton M, Reynolds K, et al. Global burden of hypertension: analysis of worldwide data. Lancet 2005;365(9455):217-23.
- Public Health England. Guidance on social distancing for everyone in the UK: UK Government; 2020 [updated 30/3/20. Available from: https://www.gov.uk/government/publications/covid-19-guidance-on-social-distancing-and-for-vulnerable-people/guidance-on-social-distancing-for-everyone-in-the-uk-and-protecting-older-people-and-vulnerable-adults accessed 6/4/20.
- Health Service Executive. At-risk groups: Coronavirus (COVID-19) 2020 [updated 5/4/20. Available from: https://www2.hse.ie/conditions/coronavirus/at-risk-groups.html accessed 6/4/20.
- British Heart Foundation. Coronavirus: what it means for you if you have heart or circulatory disease 2020 [updated 3/4/20. Available from: https://www.bhf.org.uk/informationsupport/heart-matters-magazine/news/coronavirus-and-your-health accessed 6/4/20.
- The Novel Coronavirus Pneumonia Emergency Response Epidemiology T. The Epidemiological Characteristics of an Outbreak of 2019 Novel Coronavirus Diseases (COVID-19) — China, 2020. China CDC Weekly 2020;2(8):113-22.
- Lippi G, Wong J, Henry BM. Hypertension and its severity or mortality in Coronavirus Disease 2019 (COVID-19): a pooled analysis. Polish archives of internal medicine 2020 doi: 10.20452/pamw.15272 [published Online First: 2020/04/02]
- Badawi A, Ryoo SG. Prevalence of comorbidities in the Middle East respiratory syndrome coronavirus (MERS-CoV): a systematic review and meta-analysis. International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases 2016;49:129-33. doi: 10.1016/j.ijid.2016.06.015 [published Online First: 2016/06/30]
- Wong WW, Chen TL, Yang SP, et al. Clinical characteristics of fatal patients with severe acute respiratory syndrome in a medical center in Taipei. Journal of the Chinese Medical Association : JCMA 2003;66(6):323-7. [published Online First: 2003/08/02]
- Fang L, Karakiulakis G, Roth M. Are patients with hypertension and diabetes mellitus at increased risk for COVID-19 infection? The Lancet Respiratory medicine 2020 doi: 10.1016/s2213-2600(20)30116-8 [published Online First: 2020/03/15]
- Vaduganathan M, Vardeny O, Michel T, et al. Renin–Angiotensin–Aldosterone System Inhibitors in Patients with Covid-19. New England Journal of Medicine 2020 doi: 10.1056/NEJMsr2005760
- National Institute for Health and Care Excellence. Coronavirus (COVID-19) 2020 [Available from: https://www.nice.org.uk/covid-19 accessed 6/4/20.
- Lewington S, Clarke R, Qizilbash N, et al. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet 2002;360(9349):1903-13.
- Aronson JK, Ferner RE. Drugs and the renin-angiotensin system in covid-19. Bmj 2020;369:m1313. doi: 10.1136/bmj.m1313 [published Online First: 2020/04/04]