Different classifications of nocturnal blood pressure dipping affect the prevalence of dippers and nondippers and the relation with target-organ damage

TLDR

The study aimed to evaluate how varying awake/asleep definitions and BP indices influence nocturnal BP dipping patterns, their reproducibility, and association with target‑organ damage. Researchers performed two 24‑hour ambulatory BP monitoring sessions on 150 untreated hypertensive patients, calculated left ventricular mass index and urinary albumin excretion, and classified nocturnal dipping using fixed or diary awake/asleep windows (wide or narrow) and multiple BP indices (SBP, DBP, MAP). Different awake/asleep definitions and BP indices produced substantial variability in dipping status, reproducibility, and the ability to distinguish hypertensive patients with target‑organ damage, underscoring that classification choices markedly influence the observed relationship between nocturnal dipping and organ injury.

Abstract

Objective We assessed how different definitions of the awake and asleep periods and use of various blood pressure (BP) indices affect the extent of the nocturnal BP dip, the prevalence of dippers and nondippers, their respective reproducibilities and the relation of nondipping with target-organ damage. Methods We performed 24-h ambulatory BP monitoring twice and determined the left ventricular mass index and urinary albumin excretion as indices of target-organ damage in 150 hypertensive patients (off-medication). Awake and asleep periods were assessed using fixed and diary time methods, covering all readings available (wide) or excluding morning and evening transition hours (narrow). Nondipping (BP dip < 10%) was established for systolic BP and diastolic BP, their combinations (and/or), and mean arterial pressure. Results The different awake–asleep definitions caused significant variation in both the extent of the BP dip and the number of dippers and nondippers in comparison with the wide diary definition (i.e. use of actual awake and sleep periods). The prevalences of dippers and nondippers also varied significantly with the BP index. Reproducibility analyses of the BP dip and the dipping status yielded repeatability coefficients (expressed as percentages of nearly maximal variation) between 42.39 and 48.71%, and kappa values between 0.323 and 0.459, respectively. Some classifications, but not all, discriminated significantly between consistent dippers and nondippers in terms of left ventricular mass index or urinary albumin excretion. Conclusions Use of different definitions of awake–asleep and BP indices affects significantly the classification of nocturnal BP dipping and its relation with hypertensive target-organ damage.