Association between nocturnal hypertension and composite cardiovascular outcomes in the extremely elderly population aged over 80 years

Background Nocturnal blood pressure (BP) is a better predictor of health outcomes than office or daytime BP. However, the clinical significance of nocturnal hypertension in the extremely elderly population remains unexplored. Purpose This study aimed to assess the association between nocturnal hypertension and composite cardiovascular outcomes in the extremely elderly population. Methods This was a prospective observational study including Japanese elderly outpatients aged ≥80 years. All patients underwent 24-h ambulatory BP monitoring at the baseline. Nocturnal hypertension was defined as nocturnal systolic BP (SBP) ≥120 mmHg or diastolic BP (DBP) ≥70 mmHg. Daytime hypertension was defined as daytime SBP ≥135 mmHg or DBP ≥85 mmHg. Patients were categorized into the controlled BP group, defined as daytime normotension (daytime SBP <135 mmHg and DBP <85 mmHg) and nocturnal normotension (nocturnal SBP <120 mmHg and DBP <70 mmHg); the isolated daytime hypertension group, defined as daytime hypertension with nocturnal normotension; the isolated nocturnal hypertension group, defined as daytime normotension with nocturnal hypertension; and the sustained hypertension group, defined as daytime hypertension and nocturnal hypertension. The association between those BP phenotypes and composite cardiovascular outcomes (including fatal and non-fatal cardiovascular disease and all caused mortality) was examined using Cox regression analysis. Results A total of 485 patients were followed for the mean of 3.9 years (1,734 person-years), during which 72 (14.8%) composite cardiovascular outcomes occurred. The mean age (standard deviation) was 83.2 (3.3) years; 44.7% were male; 89.3% were on antihypertensive medications. Nocturnal hypertension and daytime hypertension were present in 54.2% (n=263) and 33.6% (n=163) of patients, respectively. Compared to nocturnal normotension, nocturnal hypertension was associated with an increased risk of composite cardiovascular outcomes, even after adjustment for daytime BP values (adjusted hazard ratio [aHR]: 2.15; 95% confidence interval [CI]: 1.18-3.93). Daytime hypertension showed no such association (aHR: 1.13; 95%CI: 0.57-2.22). Both the isolated nocturnal hypertension group (n=113) and the sustained hypertension group (n=150) had a higher risk for composite cardiovascular outcomes compared with the controlled BP group (n=209): the isolated nocturnal hypertension group (aHR: 2.31; 95%CI: 1.24-4.30), and the sustained hypertension group (aHR: 2.10; 95%CI: 1.12-3.92), respectively. The isolated daytime hypertension group (n=13) did not show a significant association with composite cardiovascular outcomes (aHR: 3.23; 95%CI: 0.71-14.59). Conclusions Screening for nocturnal hypertension helps identify a high-risk group for composite cardiovascular outcomes among extremely elderly population.