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

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Systemic hypertension (n=165). Intervention: Age group (41-59 years and ≥60 years) vs. Reference age group (19-40 years). Primary outcome: 18-hour longitudinal trajectories and variability of heart rate (HR) and systolic blood pressure (SBP) across age groups.

Q: What does this research mean for the field?

In patients with systemic hypertension, 18-hour ambulatory heart rate trajectories exhibit significant age-related differences, whereas systolic blood pressure trajectories do not differ significantly across age groups. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Reka Karuppusami; M. R. Logesh; Prasanna Samuel Premkumar

doi:10.1186/s13104-026-08081-1

October 23, 2026BMC Research NotesOpen Access

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

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Key result

Ambulatory monitoring reveals distinct age-related heart rate trajectories, with four components explaining ~93% of variability.

n=165

Why the study?

Longitudinal assessment of heart rate and systolic blood pressure can clarify cardiovascular changes in systemic hypertension. This study aimed to demonstrate Functional Data Analysis on 18-hour ambulatory blood pressure monitoring trajectories and assess age-related differences in these measurements.

Does functional data analysis of 18-hour ambulatory blood pressure monitoring identify age-related differences in heart rate and systolic blood pressure trajectories in adults with systemic hypertension?

Key Points

To evaluate the use of functional data analysis for characterizing 18-hour heart rate and systolic blood pressure trajectories and assessing age-related differences in patients with systemic hypertension.
Retrospective cohort study of 165 eligible patients with systemic hypertension who underwent ambulatory blood pressure monitoring every 30 minutes (35 time points) at a hospital cardiology department in Ranipet, India.
Cardiovascular trajectories were modeled using B-splines with second-order penalization, followed by functional ANOVA (FANOVA), functional principal component analysis (FPCA), and functional linear regression (FLR) across age groups (19–40, 41–59, and ≥ 60 years).
Permutation FANOVA identified significant age-related differences in heart rate curves (notably at 150–650 and 900–1020 min), whereas systolic blood pressure trajectories showed no statistically significant differences across age groups.
Functional linear regression demonstrated dynamic, time-varying heart rate shifts in patients aged 41–59 years (maximum increase of about 3 beats/min around 650–700 min) and consistently lower heart rates in patients aged ≥ 60 years compared to the 19–40-year reference group.

Study Design

Type

Cohort (n=165)

Multicenter

No

Structured PICO

Does functional data analysis of 18-hour ambulatory blood pressure monitoring identify age-related differences in heart rate and systolic blood pressure trajectories in adults with systemic hypertension?

P

Population

165 adults (mean age 49.8 years, 32.1% female) in India with treated systemic hypertension who underwent 24-hour ambulatory blood pressure monitoring with 18 hours of analyzed longitudinal data.

E

Exposure

24-hour ambulatory blood pressure monitoring (ABPM) using an oscillometric upper-arm cuff device (Tonoport VI with Cardiosoft V7 software, GE Healthcare) recording at 30-minute intervals, with the first 18 hours of data analyzed using Functional Data Analysis (FDA) techniques (B-spline smoothing, FPCA, FANOVA, and FLR).

C

Comparator

Comparison across three age categories: 19–40 years (reference group, n=35), 41–59 years (n=92), and ≥60 years (n=38).

O

Outcome

18-hour longitudinal trajectories and variability patterns of heart rate (HR) and systolic blood pressure (SBP) measured at 30-minute intervals across age groups.surrogate

Limitations

Retrospective design limited the availability of additional clinical and demographic variables (e.g., medication use, comorbidities)
Unequal sample sizes across age groups may have affected the reliability of between-group comparisons
Relatively small sample size limited examination of additional clinical factors
Single-center hospital data from patients with systemic hypertension may limit generalizability
Analysis was restricted to an 18-hour monitoring period rather than a complete 24-hour period due to missing data beyond 18 hours
Retrospective design limited the availability of additional clinical and demographic variables
Sample size limited the ability to examine effects of medication use, comorbidities, and other patient characteristics
Analysis was restricted to an 18-hour monitoring period due to missing data beyond 18 hours, not fully representing a complete 24-hour period

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Implication

Functional data analysis of 18-hour ambulatory monitoring effectively characterizes continuous longitudinal cardiovascular patterns in hypertensive patients, revealing significant age-dependent temporal variations in heart rate trajectories that are not observed in systolic blood pressure.

Abstract

Objective Longitudinal assessment of heart rate and systolic blood pressure can provide a better understanding of cardiovascular changes in patients with systemic hypertension. This study aimed to demonstrate the application of Functional Data Analysis to analyse 18-hour cardiovascular parameter trajectories measured every 30 min using ambulatory blood pressure monitoring and to assess age-related differences in these longitudinal cardiovascular measurements. Results This retrospective cohort study included 165 eligible patients with systemic hypertension who underwent 24-hour ambulatory blood pressure monitoring at the Cardiology Department of Christian Medical College Hospital, Ranipet, Tamil Nadu, India, between July and August 2024. FANOVA showed significant age-related differences in heart rate trajectories but not in systolic blood pressure trajectories. Functional linear regression showed significant age-related changes in heart rate over time, with dynamic heart rate patterns in patients aged 41–59 years and consistently lower heart rate in those aged ≥ 60 years than the reference group. The first four functional principal components explained over 90% of the variability. Moderate heart rate variability was observed in 30.9% of patients, while 33.3% showed low systolic blood pressure variability, highlighting the ability of functional data analysis to characterise longitudinal cardiovascular patterns.

Discussion

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Cite This Study

Karuppusami et al. (2026) conducted a cohort in Systemic hypertension (n=165). Age group (41-59 years and ≥60 years) vs. Reference age group (19-40 years) was evaluated on 18-hour longitudinal trajectories and variability of heart rate (HR) and systolic blood pressure (SBP) across age groups. Functional data analysis of 18-hour ambulatory monitoring in hypertensive patients showed significant age-related differences in heart rate trajectories (with 4 FCPs explaining 92.8% of variability), while 30.9% had moderate HR variability and 33.3% had low SBP variability.

synapsesocial.com/papers/6adc8877d4862de9c273cab7 https://doi.org/10.1186/s13104-026-08081-1

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

Key Points

Study Design

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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

Key Points

Study Design

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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