Women may need lower ambulatory BP cutoffs

The ambulatory blood pressure monitoring (ABPM) cutoff for the diagnosis of hypertension should be lower in women than in men, a researcher suggested here. In a randomized trial of antihypertensive treatment, the ABPM cutoffs associated with an increased risk of cardiovascular events in men were 135/85 mm Hg for daytime and 120/70 mm Hg for nighttime, consistent with current guidelines, according to Ramón Hermida, PhD, of the University of Vigo in Spain. But the cutoffs associated with a similar cardiovascular risk in women were 125/80 mm Hg for daytime and 110/65 mm Hg for nighttime, Hermida reported at the American Society of Hypertension meeting. Along with 35 years of epidemiologic evidence that women tend to have lower blood pressure than men of the same age, the findings suggest that the ABPM threshold for starting hypertension treatment should be lower in women, even though current guidelines maintain the same cutoffs for both sexes, he said. "If we want to provide women with proper hypertension treatment, then they should be identified with a lower threshold compared with men," Hermida said. "We strongly believe the guidelines should be changed." The researchers looked at data from a study that included 1,718 men and 1,626 women (mean age 52.6) with hypertension randomized to take all prescribed antihypertensives after waking up in the morning or at least one of the medications at bedtime. The study was unique, Hermida said, in that 48-hour ABPM was performed at baseline and at least annually for every patient in the study. Patients who required adjustments in treatment underwent ABPM more frequently. Wrist actigraphy was used to objectively assess the beginning and end of daytime activity and nighttime sleep. The occurrence of cardiovascular disease events -- including cardiovascular mortality, MI, coronary revascularization, stroke, and heart failure -- was tracked through a median of 5.6 years. For blood pressure readings of 125/75 mm Hg for daytime and 110/70 mm Hg for nighttime and higher, the risk for cardiovascular events increased more rapidly for women than for men. For example, among patients with an average daytime systolic pressure of 125 to 135 mm Hg, the hazard ratio for cardiovascular events was 0.93 for men and 1.47 for women. The between-sex gap widened as blood pressure increased, such that the HRs for patients with systolic values of 165 mm Hg or higher were 2.99 for men and 7.59 for women. The blood pressure cutoffs used to diagnosis hypertension that yielded the best sensitivity and specificity for predicting increased cardiovascular risk were consistent with the guidelines for men but about 10/5 mm Hg less for women. In other words, to equal the cardiovascular risk of a man with an awake systolic pressure of 135 mm Hg, a woman only needs to achieve a systolic pressure of 125 mm Hg. Hermida noted that he and his colleagues are now corroborating the findings in another prospective study that includes about 40 clinical sites, 250 physicians and registered nurses, and 15,000 patients. Commenting on the study, Clive Rosendorff, MD, PhD, of Mount Sinai School of Medicine in New York City, said it is important for several reasons, including the large number of patients, the use of repeated 48-hour ABPM, which improves accuracy, and a long-term follow-up with hard clinical endpoints. "From all of those points of view," he said, "it's the perfect epidemiologic study and it's found something really quite startling." Primary source: American Society of Hypertension Source reference:Hermida R, et al "Gender differences in ambulatory blood pressure thresholds for diagnosis of hypertension based on cardiovascular outcomes" ASH 2012; Abstract FP-4.