Diastolic Blood Pressure Dipping During Sleep Shows Superior Unadjusted Predictive Power Compared to Systolic Dipping: A Retrospective Cohort Study.

BACKGROUND: Sleep blood pressure (BP) fall is a prognostic marker. Few studies have evaluated whether systolic BP (SBP) or diastolic BP (DBP) dipping more accurately predicts clinical outcomes. OBJECTIVE: To determine which type of BP dipping has greater predictive value for clinical outcomes. METHODS: This retrospective cohort evaluated patients who underwent ambulatory blood pressure monitoring (ABPM) between January 27, 2004, and February 16,2012. Patients were followed until the occurrence of the primary outcome (death from any cause), or until the end of follow-up period (February 01, 2022). Cox survival curves were constructed to assess which dipping classification - SBP or DBP - better distinguished the occurrence of outcomes. Dipping was defined as a nocturnal BP reduction of 10-20%. Absent and attenuated dipping were defined as reductions of ≤ 0% and 0-10%, respectively. Statistical significance was set at p < 0.05. RESULTS: A total of 756 patients were included, with a mean age of 54±16.4 years; 42% were male. In predicting the primary outcome (all-cause mortality), the absence of DBP dipping, adjusted for 24-hour SBP, was associated with a hazard-ratio (HR) of 2.051 (95% confidence interval [95%CI]: 1.147 - 3.670 (p=0.015). For the secondary outcome (cardiovascular mortality), the absence of DBP dipping, also adjusted for 24-hour SBP, showed a HR of 3.329 (95%CI: 1.317-8.412; p=0.011). In contrast, the absence of SBP dipping, when adjusted for 24-hour SBP, was not significantly associated with either outcome. In the fully adjusted model, which included age, diabetes, smoking, atherosclerotic vascular disease and chronic kidney disease, both SBP and DBP dipping lost statistically significant associations. CONCLUSION: DBP dipping demonstrates superior predictive power for outcomes compared to SBP dipping, and adds to the prognostic value of mean 24-hour SBP. (Central Illustration).