Patients with high blood pressure who take all their anti-hypertensive medication once daily at bedtime have better controlled blood pressure and a significantly lower risk of cardiovascular mortality or morbidity compared to those who take their medication in the morning, a study* published in the European Heart Journal shows.
The Hygia Chronotherapy Trial investigated the effect of the time of day when people take their anti-hypertensive medication on the risk of cardiovascular problems by randomised 19,084 patients to taking their pills on waking or at bedtime for an average of more than six years. All patients had ambulatory blood pressure monitoring over 48 hours at least once a year.
The results showed that patients who took their medication at bedtime had nearly half the risk (45% reduction) of dying from or suffering heart attacks, stroke, heart failure or requiring coronary revascularisation compared to patients who took their medication on waking. The analysis took account of factors that could affect the results, such as age, sex, type 2 diabetes, kidney disease, smoking and cholesterol levels.
When they looked at individual outcomes, the risk of death from heart or blood vessel problems was reduced by 66%, the risk of myocardial infarction was reduced by 44%, coronary revascularisation by 40%, heart failure by 42%, and stroke by 49%.
Lead researcher Professor Ramón C Hermida, director of the Bioengineering and Chronobiology Labs at the University of Vigo, Spain, said: "Current guidelines on the treatment of hypertension do not mention or recommend any preferred treatment time. Morning ingestion has been the most common recommendation by physicians based on the misleading goal of reducing morning blood pressure levels. However, the Hygia Project has reported previously that average systolic blood pressure when a person is asleep is the most significant and independent indication of cardiovascular disease risk, regardless of blood pressure measurements taken while awake or when visiting a doctor. Furthermore, there are no studies showing that treating hypertension in the morning improves the reduction in the risk of cardiovascular disease.
"The results of this study show that patients who routinely take their anti-hypertensive medication at bedtime, as opposed to when they wake up, have better-controlled blood pressure and, most importantly, a significantly decreased risk of death or illness from heart and blood vessel problems."
The Hygia Project is composed of a network of 40 primary care centres within the Galician Social Security Health Service in northern Spain. A total of 292 doctors are involved in the project and have been trained in ambulatory blood pressure monitoring. The Hygia Chronotherapy Trial is unusual in monitoring blood pressure for 48 hours, rather than the more usual 24 hours.
Data from ambulatory blood pressure monitoring showed that patients taking their medication at bedtime had significantly lower average blood pressure both at night and during the day, and their blood pressure dipped more at night, when compared with patients taking their medication on waking. A progressive decrease in night-time systolic blood pressure during the follow-up period was the most significant predictor of a reduced risk of cardiovascular disease.
Professor Hermida added: “Round-the-clock ambulatory blood pressure monitoring should be the recommended way to diagnose true arterial hypertension and to assess the risk of cardiovascular disease. In addition, decreasing the average systolic blood pressure while asleep and increasing the sleep-time relative decline in blood pressure towards more normal dipper blood pressure patterns are both significantly protective, thus constituting a joint novel therapeutic target for reducing cardiovascular risk."
*Hermida RC, Crespo JJ, Domínguez-Sardiña M, et al. Bedtime hypertension treatment improves cardiovascular risk reduction: the Hygia Chronotherapy Trial. European Heart Journal, DOI: 10.1093/eurheartj/ehz754