Blinding Assessment of Manual Therapy Interventions of the Back in Swiss Graduate Students

Study Overview
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Brief Summary
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There is marked uncertainty regarding the feasibility of achieving adequate blinding in randomized controlled trials of manual therapy. In other words, whether participants and outcome assessors can accurately perceive randomly assigned interventions is unclear. This feasibility trial was conducted as part of a doctoral epidemiology course at the University of Zurich, Switzerland. Within the practice-based context of the class and using a study population of healthy graduate students enrolled in the course, the investigators aimed to evaluate blinding of participants randomly assigned (similar to tossing a coin) to one of two manual therapy interventions (active versus control). The investigators also aimed to assess blinding among outcome assessors.

Detailed Description
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Manual therapy remains a guideline-compliant, first-line therapeutic option for back pain. Yet, maintaining methodological quality in randomized controlled trials of manual therapy interventions poses challenges, particularly concerning: (a) The design of adequate 'sham' controls and (b) the blinding status of participants and outcome assessors. Optimal implementation of large-scale manual therapy trials requires testing the feasibility of control manual therapy interventions and effective blinding of participants and outcome assessors. Even when conducted in healthy populations and non-clinical settings, blinding feasibility trials remain an opportunity for methodological advancement in the field of manual medicine, and a research priority for unbiased treatment effect estimation in future trials. The primary objective of this methodological trial was to quantitatively assess blinding feasibility among participants (graduate students enrolled in an epidemiology Ph.D. course) assigned to an active or control intervention immediately after a one-time intervention session. The secondary objective was to assess blinding feasibility among outcome assessors and explore factors influencing perceptions about intervention assignment among participants and outcome assessors. These two objectives contributed to obtaining valuable preliminary measures of blinding (blinding indices) for a future methodological blinding feasibility trial to be carried out in a real-world clinical setting.

Official Title
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Blinding Assessment of Manual Therapy Interventions of the Back in Swiss Graduate Students: a Blinding Feasibility Randomized Controlled Trial

Conditions
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Back Pain, Back Disorder, Back Pain, Low

Intervention / Treatment
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* Other: Active manual therapy
* Other: Control manual therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 years of age or older enrolled in a doctoral-level epidemiology course at the University of Zurich, Switzerland. Exclusion Criteria: serious pathology (i.e., cancer, severe scoliosis, inflammatory disease, infection, cauda equina syndrome or progressive motor deficit) history of spine surgery obvious contraindication to manual therapy (i.e., spinal fracture)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Single centre, two-parallel group, blinding feasibility randomized controlled trial.
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Active manual therapy<br>Active manual therapy intervention involved mobilization of the lumbar paraspinal musculature. With participants laying prone on a chiropractic table, the intervention provider administered hand-reinforced circumferential movements to six focal areas, using continuous ischemic compression strokes, and adjusting the pressure to participants' tolerability. | Other: Active manual therapy<br>* Soft tissue mobilization of the lumbar paraspinal musculature (3 to 4 minutes).<br>|
| Sham Comparator: Control manual therapy<br>Control MT intervention included light touch to six distal, broad areas of the thoracic region, with a synchronized breathing exercise. | Other: Control manual therapy<br>* Light touch and a breathing exercise (3 to 4 minutes).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blinding feasibility of participants, measured by the Bang blinding index. | The Bang blinding index ranges from -1 to 1, with 0 representing satisfactory blinding. It can be interpreted as the proportion of participants correctly answering their allocated intervention within an intervention arm beyond chance. For the Bang BI, a score with an absolute value of ≤0.3 (i.e., -0.3 to 0.3) was deemed compatible with satisfactory blinding, although blinding scenarios (comparing blinding indices in active vs. control arms) were discussed. Participants were asked: To which extent do you know which intervention you received? and were given five possible answers: I strongly believe I received the active intervention, I somewhat believe I received the active intervention, I somewhat believe I received the control intervention, I strongly believe I received the control intervention, and I do not know [whether I received the active or control intervention]. | Immediately after the one-time intervention session (study day 1). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blinding feasibility of participants, measured by the James blinding index. | The James blinding index ranges from 0 (all correct responses) to 1 (all 'don't know' responses), where 0.5 corresponds to 50% of responses being correct, and 50% incorrect. Lack of satisfactory blinding may be claimed if the two-sided confidence interval of the James blinding index does not cover 0.5. Immediately after the intervention, participants rated their perception about received intervention on a five-point scale: I strongly believe I received the active intervention, I somewhat believe I received the active intervention, I somewhat believe I received the control intervention, I strongly believe I received the control intervention, and I do not know [whether I received the active or control intervention]. | Immediately after the one-time intervention session (study day 1). | 
| Blinding feasibility of outcome assessors, measured by the Bang blinding index. | The Bang blinding index ranges from -1 to 1, with 0 representing satisfactory blinding. It can be interpreted as the proportion of outcome assessors who correctly answered the allocated intervention of participants within an intervention arm beyond chance. Outcome assessors were asked, To which extent do you know which intervention (active intervention or control intervention) the patient received? on a five-point scale: I strongly believe that they received the active intervention, I somewhat believe that they received the active intervention, I somewhat believe that they received the control intervention, I strongly believe that they received the control intervention, I don't know [whether this participant received active or control intervention]. | Immediately after the one-time intervention session (study day 1). | 
| Factors contributing to perceived intervention arm allocation among study participants. | Factors contributing to perceived intervention arm allocation among study participants were explored with an open-ended free text question: Please briefly explain your answer regarding the question above [question above: To which extent do you know which intervention you received?]. | Immediately after the one-time intervention session (study day 1). | 
| Factors contributing to perceived intervention arm allocation among outcome assessors. | Factors contributing to perceived intervention arm allocation among outcome assessors were explored with an open-ended free text question: Please briefly explain your answer regarding the question above [question above: To which extent do you know which intervention (active intervention or control intervention) the patient received?]. | Immediately after the one-time intervention session (study day 1). | 
| Blinding feasibility of outcome assessors, measured by the James blinding index. | The James blinding index ranges from 0 (all correct responses) to 1 (all 'don't know' responses), where 0.5 corresponds to 50% of responses being correct, and 50% incorrect. Lack of satisfactory blinding may be claimed if the two-sided confidence interval of the James blinding index does not cover 0.5. Outcome assessors were asked, To which extent do you know which intervention (active intervention or control intervention) the patient received? on a five-point scale: I strongly believe that they received the active intervention, I somewhat believe that they received the active intervention, I somewhat believe that they received the control intervention, I strongly believe that they received the control intervention, I don't know [whether this participant received active or control intervention]. | Immediately after the one-time intervention session (study day 1). | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Methods, Manual therapy, Randomised trial, Back pain, Feasibility, Blinding assessment