Association of Extreme Nocturnal Dipping with Cardiovascular Events Strongly Depends on Age

Abstract

Whether extreme dipping is associated with cardiovascular events (CVE) is unclear. The present study was conducted to test the hypothesis that the prognostic role of extreme dipping varies as a function of age. The analysis was performed in 10 868 participants (53% men) aged 53±15 (mean±SD) years enrolled in 8 prospective studies. Using the ambulatory systolic blood pressure nocturnal decline, we identified 4 groups: dippers (>10%-20%), nondippers (>0%-10%), reverse dippers (≤0%), and extreme dippers (>20%). The association between dipping category and CVE was estimated as a function of age using Cox models adjusted for sex, average 24-hour systolic blood pressure, and traditional risk factors. During a median follow-up of 5.7 years, there were a total of 829 CVE (168 fatal). For extreme dippers, no increase in risk of CVE was observed among the participants <70 years (hazard ratio, 0.99 [95% CI, 0.73-1.34]; P=0.93) compared with dippers. In contrast, among the participants ≥70 years, there was a significant increase in risk (hazard ratio, 1.88 [95% CI, 1.14-3.11]; P=0.013). Among the octogenarians, the hazard ratio (95% CI) for CVE were 2.34 (1.12-4.93) for nondippers (P=0.024), 3.91 (1.75-8.73) for reverse dippers (P=0.001), and 4.12 (1.64-10.37) for extreme dippers (P=0.003) compared with dippers. These data show that extreme dipping is not associated with poorer outcome in people younger than 70 years. A U-shaped relationship between nocturnal blood pressure dipping and adverse outcome is present in subjects older than 70 years. In the octogenarian extreme dippers, the risk of CVEs was 4× higher than in the dippers and similar to that in the reverse dippers.