Scientists pin down predictive equations for nocturnal hypertension, nondipping SBP

A group of scientists from the University of Alabama at Birmingham have derived predictive equations to identify adults at a high risk of having nocturnal hypertension or nondipping systolic blood pressure (SBP)—both hard-to-catch conditions that can raise a person’s risk for CVD.

The researchers, who outlined their findings Jan. 9 in the Journal of the American Heart Association, developed their equations using data from the long-running Jackson Heart Study and CARDIA (Coronary Artery Risk Development in Young Adults), IDH (Improving the Detection of Hypertension) and MHT (Masked Hypertension) studies. The majority of patients—2,511—were randomized to a derivation dataset, while the remaining 506 were reserved for a validation dataset. All participants underwent 24-hour ambulatory BP monitoring for their respective studies.

Byron C. Jaeger, PhD, and colleagues said in JAHA that ambulatory BP monitoring (ABPM) is the best way to identify adults with nocturnal hypertension or nondipping SBP—defined as a mean asleep SBP/diastolic BP of 120/70 mmHg or greater or an awake-to-sleep decline in SBP of 10% or less, respectively—but it’s just not practical to screen every adult in the country that way.

“A more feasible approach is to conduct ABPM screening among adults with a high probability of having these BP phenotypes,” Jaeger et al. wrote. “Therefore, we developed predictive equations to identify adults with a high probability of having nocturnal hypertension or nondipping SBP.”

Prevalence rates of nocturnal hypertension and nondipping SBP were 39.7% and 44.9% in the derivation dataset, respectively, and 36.6% and 44.5% in the validation dataset, respectively. The team’s predictive equation for nocturnal hypertension took into account age, race/ethnicity, smoking status, neck circumference, height, high-density lipoprotein cholesterol, albumin/creatinine ratio, clinical SBP and diastolic BP, and the equation for nondipping SBP was similar, accounting for age, sex/ethnicity, waist circumference, height, alcohol use, high-density lipoprotein cholesterol and albumin/creatinine ratio.

Jaeger and co-authors reported concordance statistics for nocturnal hypertension and nondipping SBP predictive equations as 0.84 and 0.73, respectively, in the validation dataset. Compared with reference models, which included antihypertensive medication use and clinical SBP and diastolic BP as predictors, the continuous net reclassification improvement values for the nocturnal hypertension and nondipping SBP predictive equations were 0.52 and 0.51, respectively.

“The equations we developed can direct ABPM screening to patients who are most likely to have nocturnal hypertension and nondipping SBP, which can be helpful in both clinical and research settings,” the researchers wrote. “ABPM is recommended by the 2017 ACC/AHA BP guideline for more than 100 million U.S. adults, but it is not widely implemented in the United States.”

Home BP monitoring is considered an alternative to ABPM, they said, but it fails to provide a measurement of nocturnal BP or nondipping SBP. The team said their equations might be useful for future research, which might enroll patients with these specific conditions to determine how to better lower nocturnal BP.

“We have developed publicly available tools for the application of these predictive equations,” Jaeger et al. said. “Application of the predictive equations may increase the efficiency and decrease the cost of ABPM screening for nocturnal hypertension and nondipping SBP.”