ArticleEmerging themes in epidemiology2017
Exploring diurnal variation using piecewise linear splines: an example using blood pressure.
Article in Emerging themes in epidemiology, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.
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5 citing papers in PubMed, 27 citations in OpenAlex.
- Fibroblasts as an in vitro model of circadian genetic and genomic studies.Mammalian genome : official journal of the International Mammalian Genome Society · 2024Article
- Fibroblasts as an in vitro model of circadian genetic and genomic studies: A temporal analysis.bioRxiv : the preprint server for biology · 2024Article
- Using linear and natural cubic splines, SITAR, and latent trajectory models to characterise nonlinear longitudinal growth trajectories in cohort studies.BMC medical research methodology · 2022Article
- Heart rate trajectories in patients recovering from acute myocardial infarction: A longitudinal analysis of Apple Watch heart rate recordings.Cardiovascular digital health journal · 2021Article
- Ambulatory blood pressure profile and stroke recurrence.Stroke and vascular neurology · 2021Article
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Authors and funding
5 authors at 4 institutions in 3 countries.
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No grant is acknowledged in the PubMed record.
Abstract
backgroundThere are many examples of physiological processes that follow a circadian cycle and researchers are interested in alternative methods to illustrate and quantify this diurnal variation. Circadian blood pressure (BP) deserves additional attention given uncertainty relating to the prognostic significance of BP variability in relation to cardiovascular disease. However, the majority of studies exploring variability in ambulatory blood pressure monitoring (ABPM) collapse the data into single readings ignoring the temporal nature of the data. Advanced statistical techniques are required to explore complete variation over 24 h.
methodsWe use piecewise linear splines in a mixed-effects model with a constraint to ensure periodicity as a novel application for modelling daily blood pressure. Data from the Mitchelstown Study, a cross-sectional study of Irish adults aged 47-73 years (n = 2047) was utilized. A subsample (1207) underwent 24-h ABPM. We compared patterns between those with and without evidence of subclinical target organ damage (microalbuminuria).
resultsWe were able to quantify the steepest rise and fall in SBP, which occurred just after waking (2.23 mmHg/30 min) and immediately after falling asleep (-1.93 mmHg/30 min) respectively. The variation about an individual's trajectory over 24 h was 12.3 mmHg (standard deviation). On average those with microalbuminuria were found to have significantly higher SBP (7.6 mmHg, 95% CI 5.0-10.1) after adjustment for age, sex and BMI. Including an interaction term between each linear spline and microalbuminuria did not improve model fit.
conclusionWe have introduced a practical method for the analysis of ABPM where we can determine the rate of increase or decrease for different periods of the day. This may be particularly useful in examining chronotherapy effects of antihypertensive medication. It offers new measures of short-term BP variability as we can quantify the variation about an individual's trajectory but also allows examination of the variation in slopes between individuals (random-effects).
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