P104 INFLUENCE OF AGE AND GENDER ON 24-HOUR VARIABILITY OF CENTRAL BLOOD PRESSURE: FINDINGS FROM THE INTERNATIONAL 24-HOUR AMBULATORY AORTIC BLOOD PRESSURE CONSORTIUM (I24ABC)

Background: Conventional brachial cuff BP is known to vary according to age and gender, but the influence of these factors on 24-hour ambulatory central BP is unknown. We sought to determine this in a large healthy population from 11 centers in Europe and Asia. Methods: 24-hour ambulatory BP using a validated oscillometric device (Mobilograph, I.E.M, Stolberg, Germany) was performed in 1645 individuals free from antihypertensive drugs. Participants were categorized as young (Y: 13–39 years; M/F:219/112), middle-aged (MA: 40–66 years; M/F:545/553), and older (O: 67–104 years; M/F:86/130). Nighttime/daytime difference (N/D) was defined as nighttime (01.00–06.00) minus daytime (09.00–21.00) values / daytime values. Results: Averaged 24-hour brachial BP was 125/79 (Y), 128/83 (MA), and 127/77 (O) mmHg. N/D for brachial SBP was −10.3% (Y), −6.4% (MA), and −4.7% (O), but was significantly less pronounced for central SBP: −1% (Y), −3.1% (MA), and −1.9% (O). Men, compared to women, had higher brachial and central SBPs, mainly in younger participants. Brachial pulse pressure (PP) displayed limited and age-dependent circadian variations, whereas central PP was substantially higher at nighttime: N/D was 24% (Y), 9% (MA), and 5.9% (O). Brachial and central PPs were higher in men in the younger group, but higher in women in middle-aged and older groups. Conclusion: Both age and gender each have a significant influence on 24-hour variability of central BP, but is different than variability in brachial BP. These data have potential implications for refining hypertension diagnosis and management.