Prognostic significance of the nocturnal decline in blood pressure in individuals with and without high 24-h blood pressure

TLDR

The study aimed to assess whether a reduced nocturnal blood‑pressure dip predicts cardiovascular mortality in people with and without elevated 24‑hour blood pressure. Using 24‑hour ambulatory BP monitoring in 1,542 Japanese adults and a 9.2‑year follow‑up, the authors applied a Cox proportional‑hazards model adjusted for confounders to evaluate the association. They found a linear link: each 5% smaller nocturnal BP decline raised cardiovascular‑mortality risk by about 20%, even among those with normal 24‑hour BP, indicating that a blunted nocturnal dip is an independent risk factor.

Abstract

To examine the relationship between the normal nocturnal decline in blood pressure and the risk of cardiovascular mortality in individuals with and without high 24-h blood pressure values.We obtained 24-h ambulatory blood pressure readings from 1542 residents of Ohasama, Japan, who were aged 40 years or more and were representative of the Japanese general population. We then followed up their survival for a mean of 9.2 years. The relationship was analysed using a Cox proportional hazards model adjusted for possible confounding factors.There was a linear relationship between the nocturnal decline in blood pressure and cardiovascular mortality. On average, each 5% decrease in the decline in nocturnal systolic/diastolic blood pressure was associated with an approximately 20% greater risk of cardiovascular mortality. There were no significant interactions for the risk between 24-h systolic/diastolic blood pressure values and continuous values for the nocturnal decline in blood pressure ( for interaction 0.6). Even when 24-h blood pressure values were within the normal range ( 135/80 mmHg, average 118/69 mmHg), diminished nocturnal decreases in systolic/diastolic blood pressure were associated with an increased risk of cardiovascular mortality.This is the first study to demonstrate that a diminished nocturnal decline in blood pressure is a risk factor for cardiovascular mortality, independent of the overall blood pressure load during a 24-h period, in the general population.