DEMOGRAPHIC FACTORS AFFECTING NOCTURNAL BLOOD PRESSURE VARIABILITY IN THE GENERAL POPULATION: RESULTS OF A LARGE DIGITAL STUDY USING AN OPTICAL BLOOD PRESSURE MONITOR

Abstract

Objective: The association between blood pressure variability (BPV) and increased cardiovascular risk is complex, and robust analyses have been limited by methodologic and statistical challenges. Short-term BVP has generally been assessed by ambulatory monitoring, and longer-term by repeated office measures. Recent advancements in optical sensors providing frequent and non-disruptive BP readings around the clock allow first characterization of night-to-night nocturnal BPV in a large population. Design and method: We nalysed 210’000 nocturnal systolic and diastolic BP (SBP, DBP) readings from 1’538 adults who wore the CE-marked Aktiia BP monitor for two weeks between April and November 2021 in Europe: mean age 56 ± 11 years, BMI 27 ± 5 Kg/m2, SBP 132 ± 14 mmHg, DBP 82 ± 10 mmHg; 15% females. For each user, we studied the variability of nocturnal BP over two weeks: we first averaged all BP readings from each night (midnight to 6am), and then calculated the standard deviation of the averaged values across nights. We finally adjusted a multivariate logistic regression to identify factors associated with high or low nocturnal BPV (defined as BPV above or below the mean of our population) based on gender, age, body mass index (BMI), and daytime home BP (measured twice by an upper-arm oscillometric cuff on day one of the monitoring period). This analysis was performed for both systolic and diastolic BPV. Results: High nocturnal systolic BPV was more likely in males (OR 1.37, CI:1.02–1.83, p = 0.035), and subjects younger than 55 years (OR 1.51, CI:1.23–1.86, p < 0.001). High nocturnal diastolic BPV was more likely in females (OR 1.63, CI:1.23–2.16, p = 0.001), and subjects with a BMI below 30 kg/m2 (OR 1.71, CI:1.32–2.20, p < 0.001). Daytime upper-arm cuff BP (systolic > = 135mmHg or diastolic > = 85mmHg) did not show a statistically significant effect in either of the two models (all p> 0.2). Conclusions: This digital investigation showed greater night-to-night variability of nocturnal systolic BP in male and young subjects, and greater variability of nocturnal diastolic BP in females and non-obese subjects. The large-scale deployment of wearable medical devices that continuously record BP enables observations that may help elucidate adverse cardiovascular risk profiles in the general population.