About this trial

The goal of this clinical trial is to test the effects of spinal manipulative therapy in individuals with chronic primary low back pain and determine the neurophysiological mechanisms underlying pain relief. The main questions it aims to answer are: • Is pain relief produced by spinal manipulative therapy in patients with chronic primary low back pain caused by a reduction of C-fiber-related nociceptive processing? • Are these effects greater when spinal manipulative therapy is applied to the whole spine where it is clinically indicated compared with lumbar spine only? • Are these effects greater after 36 treatments over 3 months compared with 12 treatments over 1 month. Participants will receive spinal manipulative therapy (all clinically indicated spine segments or back only) or a control intervention. A group of healthy volunteers will be recruited to assess secondary outcome measures over the same time period, as reference data for comparisons. Researchers will compare the two groups receiving spinal manipulative therapy to the group receiving the control intervention to see if clinical pain relief and the reduction of temporal summation of second pain (produced experimentally) is significantly greater with spinal manipulative therapy.

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

Duration of current low back pain (LBP) episode ≥ 6 months;

Average LBP intensity during the last 7 days ≥ 3/10;

(For healthy volunteers only) To be of the same sex and age (± 1 year) as a participant with low back pain.

Disqualifiers

Diagnosis of back conditions other than chronic primary LBP e.g., failed back surgery syndrome, spondylosis, spondylolisthesis, spinal stenosis, herniated disc, infection, etc.;

Presence of pain in another body location that is more severe than the pain in the lower back;

Presence of a neurological deficit i.e., sensation loss, muscle weakness, decreased deep tendon reflexes;

Presence of contraindications to spinal manipulative therapy e.g., recent fracture, history of spinal surgery, cauda equina syndrome, inflammatory arthritis, taking anticoagulant medication, active cancer, moderate to severe osteoporosis, abdominal aortic aneurysm;

Trial design

Design model

Parallel

Treatments tested in this trial

lumbar spinal manipulative therapy
Procedure/Surgery
Spinal manipulative therapy involves the application of spinal manipulation over several sessions. Spinal manipulation is defined as a high-velocity, low-amplitude thrust performed by a clinician to move a segment of the spine in a specific direction. This type of intervention often generates cavitation sounds (audible pops).
sham spinal manipulative therapy
Procedure/Surgery
Sham spinal manipulative therapy (sham SMT), was designed to be structurally equivalent to SMT, i.e., to attend to the same body regions with the same amount of contact as well as to have the same number, frequency and length of sessions. SMT and sham SMT will be provided by the same treatment provider and will appear to be similarly tailored to the participants' condition. Sham SMT does not share the component of interest of SMT, i.e., the activation of deep high-threshold mechanoreceptors via high-velocity, low-amplitude thrusts applied to the spine. Yet, it shares all the other components not of interest in this study that may contribute to the placebo response, such as therapeutic alliance, contextual factors, physical touch, and expectations. Furthermore, deception will be used to balance expectations and enhance blinding.
full spine spinal manipulative therapy
Procedure/Surgery
Spinal manipulative therapy involves the application of spinal manipulation over several sessions. Spinal manipulation is defined as a high-velocity, low-amplitude thrust performed by a clinician to move a segment of the spine in a specific direction. This type of intervention often generates cavitation sounds (audible pops).

Treatment groups

112 Participants

are divided into 4 treatment groups

Group A: lumbar spinal manipulative therapyExperimental treatment 1 intervention

Group B: full spine spinal manipulative therapyExperimental treatment 1 intervention

Group C: sham spinal manipulative therapySham comparator 1 intervention

Group D: no interventionNo intervention 0 interventions

Trial outcomes

Primary outcomes

1

low back pain intensity

In accordance with recommendations for chronic pain trials, participants will be instructed to rate the intensity of their LBP using a numerical rating scale (NRS) ranging from 0 (no pain) to 10 (worst pain imaginable). As in the brief pain inventory (BPI), they will be instructed to rate their pain: 1) right now; 2) on average over the last 7 days; 3) at its worst over the last 7 days; 4) at its best over the last 7 days.

Time frame

baseline, 1- , 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 26-, 39-, 52- and 64-weeks post-randomization.

2

temporal summation of second pain

Participants will receive a total of 160 painful laser stimuli, 80 single-pulse stimuli and 80 pulse trains (3 pulses delivered at 0.67 Hz). After each stimulus, participants will be prompted to rate second pain with the display of a numerical pain rating scale. The pain ratings of single pulses will be subtracted from the pain ratings of pulse trains to estimate the intensity of the temporal summation of second pain.

Time frame

baseline, 4- and 12-weeks post-randomization.

Secondary outcomes

1

low back pain frequency and duration

A modified version of the pain frequency-severity-duration scale will be used. Participants will be instructed to answer these 3 questions: * Is the pain recurrent (it comes in episodes) or continuous (it is always present)? * How many days in the past week have you had low back pain? (0, 1, 2, 3, 4, 5, 6, 7 days; a higher score means a worse outcome) * On average, how many hours per day does the pain last? (0; 1-4; 5-8; 9-12; 13-16; 17-20; 21-24 hours; a higher score means a worse outcome)

Time frame

baseline, 1- , 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 26-, 39-, 52- and 64-weeks post-randomization.

2

Pressure pain thresholds (PPTs)

PPT will be measured using a handheld digital algometer (Wagner Pain TestTM FPX, Greenwich, Connecticut, USA) and a standardized protocol. The algometer will be applied perpendicularly to the skin of the first test location and the pressure increased at approximately 50 kPa/s until pain is reported by the participant. This procedure will be repeated three times at the same test location. The PPT will be the average of the values obtained during these 3 trials. The same procedures will be repeated at the two other test locations. PPT will be tested on three different body locations: 1) Over the spinous process of the most painful vertebra between L1 and S1; 2) On the right lower limb in the dermatome corresponding to the level of the most painful vertebra; 3) in the center of the right thenar eminence.

Time frame

baseline, 4- and 12-weeks post-randomization.

3

C-fiber-related brain responses

Electroencephalography (EEG) will be recorded using a 64-channel BrainVision system with active Ag-AgCl electrodes mounted on an actiCAP, according to the International 10-20 system (Brain Products, Gilching, Germany). Electrodes will be nose-referenced, and the ground will be set at FPz. Signals will be sampled at 500 Hz. Eye movements and blinks will be recorded using electrooculography (EOG). Electrode impedance will be kept below 20 kΩ. Closed eyes resting state EEG will be recorded for 5 min prior to laser stimuli for exploratory EEG analyses. EEG activity will be recorded continuously. The outcome of interest from laser-evoked-brain activity is the response evoked by C-fiber activation. Laser-evoked potentials (LEP) and event-related spectral perturbations (ERSP) will be analyzed using validated methods.

Time frame

baseline, 4- and 12-weeks post-randomization.

4

Oswestry Disability Index (ODI)

Self-reported low back pain related disability will be evaluated using the French-Canadian version of the ODI (0-100%; a higher score means a worse outcome).

Time frame

baseline, 4-, 12-, 26-, 39-, 52- and 64-weeks post-randomization.

Other outcomes

1

Adverse events (AE)

Participants will be informed of the risk of AE and the importance to communicate any unpleasant or abnormal sensation occurring in the hours or days following a treatment. Mild AE are defined as transient reactions (≤ 48 h) that do not require further treatment. Moderate AE are defined as reactions lasting more than 48 h, limiting function or daily activity and possibly requiring additional care. Severe AE are defined as reactions requiring hospital admission, life threatening, or causing long-lasting disability.

Time frame

1- , 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 13-weeks post-randomization.

2

Blinding

Blinding will be assessed by asking these questions: 1) Do you think that you received a real chiropractic treatment for low back pain? (yes / no) 2) How certain are you on a scale of 0 to 10, where 0 indicates certainty of not having received a chiropractic treatment, 5 indicates absolute uncertainty, and 10 absolute certainty of having received a chiropractic treatment

Time frame

After the last treatment session (12-weeks post-randomization)

3

Number of other treatments for low back pain

Participants will be informed about the possibility to seek care for their low back pain outside the study at any point, if necessary. Based on recent Canadian practice guidelines for chronic LBP, exercise and oral nonsteroidal anti-inflammatory drugs (NSAIDs) will be recommended as first alternatives to interventions provided in the study. However, participants may receive other treatments. The number of concomitant treatments will be measured once a week by asking these questions: * In the past 7 days, have you used or received any other treatment for low back pain than the one provided in this study? (yes / no) * If so, please specify the number of treatments you received (for example: the number of pills taken, the number of therapy sessions, etc.).

Time frame

1- , 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-weeks post-randomization.

The METRIC Study Protocol

About this trial

Eligibility criteria

Qualifiers

Disqualifiers

Trial design

Treatments tested in this trial

Treatment groups

Trial outcomes

Primary outcomes

Secondary outcomes

Other outcomes

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