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Pragmatic Pilot Randomised Controlled Trial of Autonomic Nervous System Responses to Chiropractic Care: Assessment of Feasibility

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Thesis embargoed until 15th November 2026(10.31 MB)

Date

2024

Authors

Supervisor

Olsen, Sharon
Thoma, Christian
Niazi, Imran

Item type

Thesis

Degree name

Master of Health Science

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Publisher

Auckland University of Technology

Abstract

Background & Rationale: There has been significant growth in understanding of the role of the autonomic nervous system (ANS) in health. Research has shown correlations between autonomic dysfunction and various clinical disorders, and this has led to an expansion of research to identify modalities that have the potential to positively impact the ANS. In parallel, the field of research into the neurophysiological basis of chiropractic care has grown rapidly over the last two decades, demonstrating central nervous system (CNS) changes following chiropractic adjustments. There is currently limited evidence about the effect of chiropractic adjustments on the ANS. However, evidence from the broader field of spinal manipulative therapy suggests that chiropractic care has potential to modulate a number of ANS outcomes including heart rate variability (HRV), skin conductance, and pupillometry. These positive results, combined with the advance in technologies capable of measuring the ANS outside a laboratory setting, provide a rationale for conducting a multivariable pragmatic randomised control trial (RCT) assessing the effects of chiropractic care on ANS responses. Prior to conducting a fully-powered RCT, the feasibility of the protocol must be established. Objectives: The primary objective of this study was to determine the feasibility of this pilot pragmatic RCT protocol. This would inform recommendations for a future fully-powered trial. Methods: Twenty adults with subclinical musculoskeletal pain were randomised to either the ‘chiropractic’ group or the ‘hands-on active control’ group for a 6-week intervention. The chiropractic group received twice-weekly sessions involving full spine examination and chiropractic spinal adjustments that were individualised to each participant. The control group received once-weekly sessions involving full spine examination but no chiropractic spinal adjustments. The interventions were delivered by a NZ registered chiropractor in a small urban chiropractic clinic in New Plymouth, New Zealand. Both groups were prescribed daily stretches to complete at home. At the pre- and post- intervention assessments, the following data were collected: heart rate variability (HRV), skin conductance, pupillometry and functional near infrared spectroscopy (fNIRS) before, during and after a cold pressor test, and a quality-of-life questionnaire (PROMIS-29). During the intervention period, continuous HRV and sleep quality data were collected using a wearable monitor (FitbitTM smartwatch). The feasibility of the protocol was determined through evaluation of the following outcomes: recruitment, retention, protocol deviations, adherence, intervention fidelity, data completeness, safety, and acceptability. Results: The findings demonstrated that the RCT protocol was feasible with only minor protocol deviations required. With the exception of adherence to the home stretching exercise programme (69%), all the feasibility criteria thresholds were met: 20 participants were recruited within the allocated timeframe, only one participant dropped out for a reason unrelated to the study; all participants completed 80% of the planned sessions; >95% of pre- and post-intervention ANS data and >92% of the continuous ANS data were collected; 84% of the participants were satisfied with the study; and no safety concerns were reported. Of note, the participants had high adherence to wearing the FitbitTM smartwatch for the duration of the study. Conclusions: This study has given valuable insights about the feasibility of conducting a pragmatic RCT, in the field, measuring the effects of multiple weeks of chiropractic care on the ANS. The recording of multiple ANS measures and continuous measurements through the use of a wearable device represented a novel combination of data collection to which participants responded favourably. In particular, it was promising that despite the high time burden of the study, participants in both groups had high adherence to the interventions and there was a low dropout rate. Based on the findings from this study, a number of recommendations have been made for the design of a future fully-powered RCT that would assess the magnitude of the treatment effect in a subclinical pain population. In addition, future trials should determine whether ANS responses to chiropractic care are associated with clinically meaningful changes in health outcomes, and investigate effects in a clinical population.

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http://hdl.handle.net/10292/18326

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