SIMPLIFIED AMBULATORY NIGHTTIME BLOOD PRESSURE MONITORING IS ASSOCIATED WITH THE RISK OF TARGET ORGAN DAMAGE AND BETTER ADHERENCE

Objective: Nighttime blood pressure (BP) is a more sensitive indicator of cardiovascular events. However, frequent nocturnal BP monitoring may decrease reproducibility and adherence. Therefore, this study aimed to investigate whether reducing the frequency of nighttime BP measurements or utilizing awake BP readings could effectively reflect nighttime hypertension and associated target organ damage. Design and method: A total of 2475 hypertensive patients with complete ambulatory BP monitoring data, who visited the Hypertension department of our hospital between January 2015 and October 2020, were recruited in this study. We assessed five systolic blood pressure (SBP) measurement indicators: (1) fixed-interval SBP at three time points (average of SBP measured at 2:00 am, 3:00 am, and 4:00 am), (2) extended-interval SBP at three time points (average of SBP measured at 11:00 pm, 2:00 am, and 5:00 am), (3) bedtime SBP, (4) morning SBP, and (5) average daytime SBP, to evaluate the diagnostic value for nighttime hypertension. We further explored the association between these SBPs and target organ damage in multivariate logistic analysis. Results: 1873 (75.7%) patients were diagnosed as nighttime hypertension. Among the five indicators, fixed-interval SBP showed the strongest correlation with average nighttime SBP (r=0.961, p<0.001). The Bland-Altman and intraclass correlation coefficients (ICC) indicated good consistency with a bias of 0.8 mmHg (95% CI 0.6–1.0), and limits of agreement ranging from -9.0 to 10.6 mmHg, with 95.1% data points falling within this range (ICC=0.96). Compared to other four indicators, fixed-interval SBP demonstrated the best diagnostic ability for nighttime hypertension (AUC=0.974 [95%CI: 0.969-0.979], p<0.001). The optimal cut-off was 120.5 mmHg with sensitivity of 90.7% and specificity of 91.4%. Furthermore, fixed-interval SBP exhibited a J-shaped association with left ventricular hypertrophy (3.2 [95%CI 2.7-3.9], p<0.001), arterial stiffness (3.5 [2.9-4.2], p<0.001), and proteinuria (3.2 [2.7-3.8], p<0.001) after adjusting for confounding factors. Conclusions: Consistent with conventional seven-time-point SBP measurements, the fixed-interval SBP measured at three time points also showed significant diagnostic value for nighttime hypertension, and was associated with increased risk of target organ damage. This simplified indicator has the potential to enhance patient adherence by improving sleep comfort while maintaining accuracy.