Resistant high blood pressure link to 'white coat' syndrome

One in three patients affected

One in three cases of high blood pressure that don't respond to treatment may be caused by "white coat syndrome," a study has found. White coat syndrome is used to describe the phenomenon in which a patient's blood pressure is unusually high when measured by a doctor, but returns to normal once they leave the GP's surgery. It is thought to be caused by nerves.

In a large study, researchers monitored the blood pressure of nearly 70,000 patients with hypertension, or high blood pressure. Of these, around 8,000 of the patients also had resistant hypertension, which did not respond to treatment, despite taking as many as three different drugs at the same time. All of the patients wore a portable device, which measured their blood pressure at 20 minute intervals day and night.

The findings showed that around 37 per cent of the patients thought to have resistant high blood pressure actually had white coat syndrome, after being monitored for 24 hours. The remainder had genuine resistant high blood pressure. White coat syndrome was also more common in women (42 per cent) than men (34 per cent).

Study leader Dr Alejandro de la Sierra from the University of Barcelona said: "Those with true resistant hypertension showed high blood pressure at work, during the day and at night. "The true resistant group also was more likely to have blood pressures that abnormally rose during the night when they were sleeping."

The study, published in the journal Hypertension, also found that patients with genuine resistant high blood pressure were more likely to be smokers, diabetics, and patients with risk factors or a history of heart disease. Dr de la Sierra concluded: "Physicians should be encouraged to use ambulatory monitoring to confirm resistant hypertension in their patients as it would ensure the most effect treatment options are used.

"Patients benefit by knowing whether their blood pressure is normal during daily activities or still needs the reinforcement of dietary and drug measures to achieve the goal." The UK National Institute for Clinical Excellence has proposed that people with two high blood pressure readings should take a third at home to rule out ‘white coat’ syndrome in draft guidance currently under consultation.

The Family GP