Objective: To evaluate whether the nocturnal blood pressure fluctuation (NBPF) index provides incremental value for risk stratification of obstructive sleep apnoea beyond established demographic, anthropometric, and clinical screening variables, including nocturnal dipping, and to assess its potential role as a novel risk marker. Design and method: We analysed recordings from a large sleep laboratory cohort. NBPF was quantified as the absolute count of nocturnal blood pressure increases exceeding 12 mmHg and standardised relative to age- and sex-specific expectations. The primary outcome was moderate-to-severe sleep apnoea, defined as an apnoea–hypopnoea index (AHI) > 15 events/hour. Logistic regression models were constructed using age, sex, and body mass index (BMI) as a baseline screening model and compared with extended models including NBPF and nocturnal dipping. Model discrimination was assessed using the area under the receiver operating characteristic curve (AUC), likelihood ratio testing, and effect size estimates. Results: Among 1,162 diagnostic sleep studies, the prevalence of AHI > 15 was 51.0%. Higher NBPF relative to age and sex was consistently associated with increased sleep apnoea severity. Each 10% increase in NBPF above the expected value was associated with a 5% higher odds of AHI > 15 (odds ratio 1.05, 95% confidence interval 1.04–1.07). The baseline screening model including age, sex, and BMI achieved an AUC of 0.70, which improved to 0.74 after addition of NBPF (dAUC = 0.04; likelihood ratio p < 0.001). Empirical risk increased stepwise across NBPF strata, ranging from approximately 39% in individuals with markedly lower-than-expected NBPF to over 75% in those with extreme elevations. In contrast to nocturnal dipping, NBPF provided substantial incremental predictive value, and model performance deteriorated markedly when NBPF was omitted. NBPF showed a stronger association with respiratory-related sleep disturbances than with non-respiratory contributors, supporting its physiological specificity.Conclusions: NBPF provides clinically relevant, independent information for sleep apnoea risk stratification beyond age, sex, BMI, and nocturnal dipping. Incorporation of this novel, age-adjusted nocturnal blood pressure marker meaningfully improves screening performance and may enable more targeted referral for diagnostic sleep studies.
Bothe et al. (Fri,) studied this question.