Ambulatory 24-hour BP better predicts mortality
Twenty four-hour ambulatory blood pressure (BP) measurements better predict all-cause mortality and cardiovascular (CV) mortality than clinic BP measurements, according to data from the Spanish Ambulatory Blood Pressure Registry.
Among 66,636 adults recruited between 2004 and 2014 who were followed up for a median of 4.7 years, 24-hour systolic BP was more strongly associated with all-cause mortality and CV mortality (hazard ratio [HR], 1.58 for both after adjustment for clinic BP) than clinic systolic BP (HR, 1.02 for both after adjustment for 24-hour BP). The HRs were 1.55 and 1.54 for night-time ambulatory systolic BP and daytime ambulatory systolic BP, respectively. [N Engl J Med 2018;378:1509-1520]
According to the investigators, the associations between ambulatory BP measurements and mortality were consistent across subgroups of age, gender, and status with respect to obesity, diabetes, CV disease and antihypertensive treatment.
Unlike most previous studies, masked hypertension (MH) was found to be a stronger predictor of all-cause mortality (HR, 2.83) than sustained hypertension (HR, 1.80) or white-coat hypertension (HR, 1.79), with similar results also shown for CV mortality. The investigators suggested that this might be due to the delayed detection of MH, which could result in more organ damage and CV disease in patients.
Masked uncontrolled hypertension was found to be associated with high mortality in the subpopulation of patients with treated hypertension and controlled clinic BP who died (population attributable fraction, 33.3 percent).
The results also show that white-coat hypertension is not benign, although previous research demonstrated a mortality risk similar to that of normotension or an intermediate risk between normotension and hypertension. According to the investigators, this might be due in part to the higher mean 24-hour BP in patients with white-coat hypertension in the current study (119.9/71.9 mm Hg vs 116.6/70.6 mm Hg in normotensive patients; p<0.001) or to the patients’ metabolic phenotype.