Functional Data Analysis Tracks Heart Rate Patterns in Hypertension Patients

A retrospective cohort study published in BMC Research Notes has applied Functional Data Analysis to 18-hour heart rate and systolic blood pressure trajectories recorded in patients with systemic hypertension, revealing significant age-related differences in heart rate patterns that conventional summary measures may overlook.

The study included 165 eligible patients with systemic hypertension who underwent 24-hour ambulatory blood pressure monitoring at the hospital between July and August 2024. Measurements were taken every 30 minutes, producing dense longitudinal trajectories of heart rate and systolic blood pressure across an 18-hour window. Using Functional Analysis of Variance, or FANOVA, the researchers found significant age-related differences in heart rate trajectories, but not in systolic blood pressure trajectories, suggesting that age shapes the dynamic course of heart rate over the monitoring period more distinctly than it shapes blood pressure curves in this cohort.

Functional linear regression added detail to this finding. The analysis showed significant age-related changes in heart rate over time, with dynamic heart rate patterns observed in patients aged 41 to 59 years, while patients aged 60 and older showed consistently lower heart rate than the reference group. Because the study is retrospective and observational, these patterns describe associations within a single-centre cohort rather than causal effects, and the findings reflect the monitored 18-hour period rather than long-term cardiovascular outcomes.

The researchers also examined how much of the variability in the curves could be captured by a small number of components. The first four functional principal components explained over 90 percent of the variability in the data, indicating that the complex 30-minute-interval recordings could be compressed into a handful of interpretable patterns without substantial loss of information. Alongside these curve-based summaries, the study reported conventional variability categories: moderate heart rate variability was observed in 30.9 percent of patients, while 33.3 percent showed low systolic blood pressure variability.

The authors position the work as a demonstration of method rather than a clinical trial. Longitudinal assessment of heart rate and systolic blood pressure, they note in the study’s objective, can provide a better understanding of cardiovascular changes in patients with systemic hypertension, and Functional Data Analysis offers a way to assess these measurements as whole trajectories. The approach treats each patient’s series of readings as a smooth function, allowing tests of how covariates such as age relate to the shape of the curve over time. As a Research Note based on 165 patients from one cardiology department over a two-month recruitment window, the study’s value lies chiefly in illustrating the analytical technique and in its specific observation that age relates to heart rate trajectories but not to systolic blood pressure trajectories in this group.

Subject of Research: Application of Functional Data Analysis to 18-hour heart rate and systolic blood pressure trajectories in patients with systemic hypertension

Article Title: Functional data analysis of 18-hour heart rate and systolic blood pressure variability in patients with systemic hypertension: a retrospective cohort study

Article References: Karuppusami, R., Ravi, L. M., & Premkumar, P. S. (2026). Functional data analysis of 18-hour heart rate and systolic blood pressure variability in patients with systemic hypertension: a retrospective cohort study. BMC Research Notes. https://doi.org/10.1186/s13104-026-08081-1

Image Credits: AI Generated

DOI: 10.1186/s13104-026-08081-1

Keywords: hypertension, heart rate variability, blood pressure, functional data analysis, ambulatory blood pressure monitoring, retrospective cohort study, FANOVA, functional principal components, cardiology, age-related differences, Functional, data