Getting the measure of high blood pressure

There have been many developments in the management and research of high blood pressure, or hypertension, which is now the world’s leading cause of death and disability (ahead of cancer, Aids and malnutrition). It affects more than a million people in Ireland, the majority of them over 60.

It is the major cause of the 10,000 strokes that occur annually in Ireland. If blood pressure was restored to normal, at least half of these strokes would be prevented, and there would be a significant reduction in cognitive impairment, dementia and heart attack.

To halt the increasing devastation being caused by hypertension, medical scientists have been working on ways to improve the diagnosis and management of the condition; some of the important ones are summarised here. Drug treatment Almost everyone with high blood pressure requires drug treatment in addition to lifestyle modification such as stopping smoking, reducing their salt and cholesterol intake, moderating alcohol consumption, weight reduction and taking regular exercise.

Most people with high blood pressure will require more than one drug. It is possible to use lower doses of combined drugs, thus avoiding unwanted effects, than using a full dose of one drug.

However, understandably, people with high blood pressure don’t like taking a number of tablets and the pharmaceutical companies have made combination preparations containing the most effective classes of blood-pressure-lowering drugs in differing doses in one tablet.

These “single pill combinations” have been a major advance in allowing doctors to prescribe differing doses of two or three dugs without having to give the patient more than one tablet.

This development has removed one of the main barriers to achieving blood pressure control, namely poor adherence to treatment by patients who resent the need to take multiple drugs.

Ambulatory blood pressure measurement (ABPM) The only way to find out if blood pressure is raised, and to judge the effect of treatment, is by measuring blood pressure.

Recently I led a group of 34 international experts from the European Society of Hypertension in drawing up guidelines for the best way to measure blood pressure.

The group concluded firstly that high blood pressure should never be diagnosed on the basis of blood pressure measurements in a doctor’s surgery or hospital clinic. This can cause momentary elevation of blood pressure in as many as 20 per cent of people, known as white-coat hypertension, and can miss elevation of blood pressure in many more, known as masked hypertension.

The group recommended that people who have ever been told that they had a high blood pressure measurement should have ambulatory blood pressure measurement (ABPM) to confirm or dismiss the diagnosis, and that patients on blood-pressure-lowering drugs should have their treatment managed by ABPM. However, ABPM is not available for many people with high blood pressure.

Accessibility of ABPM in Irish pharmacies Ireland leads the world in being the first country to provide ABPM in pharmacies, in addition to GP surgeries, and hospital and private clinics.

In a recent Irish study using specialised software that allowed central collection, analysis and comparison of ABPM data from thousands of patients attending their GPs and local pharmacies, it was shown that the information from pharmacy-recorded ABPM was as good as that from general practice. This means that the availability of ABPM in pharmacies permits many patients with hypertension to avail of the technique. It is anticipated that this will greatly improve the management of hypertension.

Disappointing result for kidney technique to 'cure' hypertension Few topics have generated as much interest as the technique of renal denervation, which consisted of passing a small tube into the arteries supplying the kidneys and then burning the nerve supply to the kidneys.

Enormous sums of money were invested in the procedure, with thousands of publications in medical literature. The lay press hailed the technique as the greatest medical innovation to have happened in recent times, and one that would not only cure hypertension but would improve heart failure, diabetes mellitus, sleep apnoea and irregularities of the heart.

It was anticipated that patients might be permanently cured of hypertension without the need for drugs. But there were warnings from cautious experts, who questioned the impetus for a treatment that was based on economic, rather than scientific, considerations.

They warned that the procedure, although apparently safe in the short term, might cause long-term damage to the kidneys. Nonetheless, the technique was approved in several European countries. It was not approved in the US.

Then, in January 2014, a press release from Medtronic, the major investor in the procedure, declared that a study it had sponsored had shown the technique to be ineffective.

It is estimated that 5,000-10,000 patients around the world, some of them in Ireland, underwent this procedure and they might justifiably ask whether they might not have been spared an ineffective and expensive procedure that may not be without long-term risk.

The message for patients with high blood pressure is clear. No one should undergo this procedure until more information becomes available from carefully conducted scientific studies, which will take some years to complete.

Awareness about high blood pressure It is estimated that about one in four adults have hypertension, which equates to about 1 billion individuals around the world, and this number is expected to grow to 1.5 billion (30 per cent of the global adult population) by 2025. Many of these people do not understand the importance of high blood pressure as a major cause of stroke and heart attack, or that it can be easily managed and that the catastrophic consequences can be prevented.

In an effort to provide information I wrote an app, BP Expert, and this has been downloaded by more than 10,000 people who are now more aware about high blood pressure and its consequences.

This app has been revised and will be made freely available so that Ireland can lead globally in the drive to achieve better control of hypertension with a reduction in stroke and the other cardiovascular consequences of the condition.

Eoin O’Brien is professor of molecular pharmacology at the Conway Institute, UCD