An observational study of patients with mild hypertension has found no evidence to support recent US guideline recommendations that encourage doctors to offer treatment to patients with low-risk mild hypertension.

Researchers from the University of Oxford, Cambridge University and the University of Birmingham looked at the routinely collected medical records of more than 38,000 patients in the UK over a period of 15 years. The patients were aged between 18 and 74, had mild hypertension (UK stage 1: 140-159/90-99mmHg) and had not received any previous treatment for the condition. They compared patients who went on to be treated with antihypertensive medication to those who were not, and found the treatment had no benefit and did not reduce their risk of heart attack or stroke. However, there was evidence of an increased risk of adverse events over the follow-up period of five-to-six years, such as hypotension (low blood pressure), fainting or kidney damage.

Dr James Sheppard from Oxford University’s Nuffield Department of Primary Care Health Sciences, who led the study, said: 'We found that, contrary to the latest guideline recommendations, there was no evidence of any benefit to treating patients with low-risk mild hypertension. This suggests that doctors should be cautious when considering hypertension treatment in this group and we would therefore encourage a conversation between a patient and their doctor to decide the best way to treat the condition. Younger patients in particular may prefer to adopt lifestyle changes to reduce their blood pressure, rather than committing to taking antihypertensive drugs for many years.'

'Being an observational study, our data should be interpreted with caution since these studies can sometimes give biased results. The best quality evidence for making clinical decisions comes from clinical trials, yet there are occasions where trials have not been done, or are not possible and so decision-makers rely on expert opinion to form clinical guidelines. To ensure future guideline recommendations for treating low-risk mild hypertension are based on the best-quality evidence, large-scale clinical trials are now needed.'

Jonathan Mant, Professor of Primary Care Research and Head of the Primary Care Unit at the University of Cambridge, said: 'Given that we found tangible evidence of the potential harm of treating people with mild hypertension, and no evidence of benefit, this study does raise questions over the value of initiating drug treatment in such patients.'

The National Institute for Health and Care Excellence (NICE) is currently reviewing its guidelines for treating people with hypertension, which are due to be announced next year.

The study was funded by the Medical Research Council and was supported by the National Institute for Health Research.

The full paper, ‘Benefits and harms of antihypertensive treatment in low-risk patients mild hypertension,’ can be read in JAMA Internal Medicine.