Autonomic Differences in Heart Rate Variability Between Healthy and Chronic Low Back Pain Subjects

Cross-Sectional Analysis of Autonomic Differences in Heart Rate Variability Between Healthy Individuals and Subjects with Chronic Low Back Pain

This study aims to evaluate the autonomic differences in heart rate variability (HRV) between healthy individuals and those with chronic low back pain. By analyzing HRV parameters, such as time-domain, frequency-domain, and non-linear metrics, this cross-sectional study seeks to explore the impact of chronic pain on the autonomic nervous system. The study will provide insights into parasympathetic and sympathetic modulation and its potential relationship with chronic pain symptoms. Participants include healthy adults and individuals with chronic low back pain aged 18-65.

Study Overview

• Status: Completed
• Conditions: Heart Rate Variability; Autonomic Nervous System Dysfunction; Chronic Low Back Pain (CLBP)

• Study Type: Observational
• Enrollment (Actual): 98

Contacts and Locations

Study Locations

• Spain
  • Badajoz, Spain, 06006
    • Universidad de Extremadura

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

The study includes two groups: one group of adults diagnosed with chronic low back pain, aged 18-65 years, and another group of healthy adults within the same age range. Participants were recruited from local community advertisements and hospital outpatient clinics.

Description

Inclusion Criteria:

• Adults aged between 18 and 65 years.

For the chronic low back pain group:

• Diagnosis of chronic low back pain lasting at least three months.
• A minimum pain intensity of 3/10 on the Numerical Pain Rating Scale (NPRS).

For the healthy group:

• Absence of any chronic or acute pathology.
• No regular medication that could alter autonomic nervous system function.
• No episodes of low back pain in the past six months.

Exclusion Criteria:

• Presence of uncontrolled neurological or cardiac disorders.
• Use of medications that could influence autonomic function or pain perception (e.g., opioids, antidepressants, benzodiazepines, anti-inflammatory drugs, beta-blockers) within two weeks prior to the study.
• Body Mass Index (BMI) equal to or greater than 30 kg/m².

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Healthy Subjects; This group includes adults aged 18-65 years without any chronic or acute pathology, no regular medication that could alter autonomic nervous system function, and no low back pain in the past six months.
Chronic Low Back Pain Subjects; This group includes adults aged 18-65 years diagnosed with chronic low back pain lasting at least three months, with a minimum pain intensity of 3/10 on the Numerical Pain Rating Scale, and without uncontrolled neurological or cardiac disorders.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Root Mean Square of Successive Differences (rMSSD)	This variable represents a time-domain measure of heart rate variability, reflecting parasympathetic nervous system activity and short-term variability in R-R intervals. It is calculated as the root mean square of differences between successive R-R intervals. rMSSD is an established metric to assess vagal modulation and is sensitive to changes in autonomic function.	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
SD1 (Short-Term Variability)	A non-linear metric derived from the Poincaré plot of heart rate variability, indicating short-term variability in R-R intervals. It is closely associated with parasympathetic activity and vagal modulation.	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
SD2 (Long-Term Variability)	A non-linear metric derived from the Poincaré plot, representing long-term variability in R-R intervals. SD2 is inversely related to sympathetic activity and reflects the balance between sympathetic and parasympathetic modulation.	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Stress Score (SS)	This variable is calculated as the reciprocal of SD2, multiplied by 1000. It reflects the level of sympathetic activation, where higher Stress Score values indicate increased stress and reduced parasympathetic activity.	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Sympathetic/Parasympathetic Ratio (S/PS Ratio)	This variable represents the ratio of Stress Score to SD1. It reflects the balance between sympathetic and parasympathetic modulation, with higher values indicating sympathetic dominance, commonly observed in chronic pain conditions.	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Heart Rate (Mean HR)	Represents the average heart rate (beats per minute) recorded during the data collection period. It serves as a general indicator of autonomic activity, providing insights into the balance between sympathetic and parasympathetic modulation.	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Minimum Heart Rate (Min HR)	Represents the lowest heart rate (beats per minute) recorded during the data collection period. This variable reflects periods of parasympathetic predominance and is useful for assessing vagal	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Maximum Heart Rate (Max HR)	Represents the highest heart rate (beats per minute) recorded during the data collection period. This variable reflects periods of sympathetic activation and provides insights into stress responses during the session.	Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.

Collaborators and Investigators

• Sponsor: Universidad de Extremadura
• Investigators: Study Director: Luis Espejo-Antúnez, Ph.D., University of Extremadura

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2020
• Primary Completion (Actual): November 30, 2020
• Study Completion (Actual): November 30, 2020

Study Registration Dates

• First Submitted: December 29, 2024
• First Submitted That Met QC Criteria: December 29, 2024
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: December 29, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Back Pain; Low Back Pain
• Other Study ID Numbers: 08

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No