Which Exercise for Low Back Pain? Predicting Response to Exercise for Patients With Low Back Pain

Exercise therapy is the most recommended treatment for chronic low back pain. There is a wide range of exercises available and research studies have shown that no exercise is superior to another. The problem is that the effects of exercise in reducing pain and disability are small to moderate. Researchers and clinicians believe that different patients may best respond to different types of exercises. This means that if patients could be better matched to specific exercises, then the effects of exercise would be greater. A study conducted by the investigators of this study tested whether patient's characteristics could predict outcomes to two of the most common exercises for low back pain: motor control exercises or graded activity. The results showed that a simple questionnaire (Lumbar Spine Instability Questionnaire) could identify patients who responded best to either exercise. Patients with low clinical instability (measured by the questionnaire) responded best to graded activity. Patients with high clinical instability responded best to motor control exercises.These results were the first to show that better matching patients to specific exercises improves outcomes. Although these results have the potential to significantly improve the delivery of exercises for low back pain, validation of the results in a high-quality study with a large group of patients is a prerequisite to clinical implementation. The aim of this study is to conduct a randomized controlled trial comparing the effects of graded activity to motor control exercises and identify groups of respondents to these exercises. The study will also include the evaluation the costs and benefits of these interventions and the potential impact of matched treatment to patients and the health care system. The results of this study has the potential to increase the effects of exercise in low back pain and consequently lead to better patient outcomes and decreased health related costs.

Background:

Clinical practice guidelines consistently endorse exercise therapy for the treatment of low back pain (LBP). While exercise is more effective than no intervention, the effect size of exercise, like other treatments for LBP, is relatively small. While there are many forms of exercise therapies available (e.g. general exercise, pilates), there is no clear evidence of superiority of one exercise over another. A widely held belief is that the small effect for exercise is due to the heterogeneity of people presenting with LBP and if individual patients could be better matched to the optimal types of exercise, then the effects of treatment would be greater.A recently published study conducted by the study investigators provided preliminary evidence supporting the hypothesis of better outcomes when patients are matched to the appropriate exercise. The study demonstrated that a simple 15-item questionnaire, the Lumbar Spine Instability Questionnaire (LSIQ), could identify patients who responded best to either of the most common exercise approaches for LBP. Participants who had low scores on the LSIQ had better outcomes with graded activity while those with higher scores had better outcomes with motor control exercise. Theoretically, motor control would work best on those that have poor coordination and control of the trunk muscles and graded activity would work best on those with unhelpful beliefs and attitudes towards back pain. Although the results of this study have the potential to transform exercise treatment for LBP, validation and confirmation off the results in a fully powered study using an independent sample is essential before recommending implementation in clinical practice. Validation and impact analysis are crucial steps in the investigation of effect modification models.

Research aims:

The primary aim of this study is to evaluate whether pre-identified baseline characteristics, including the LSIQ, can modify the response to two of the most prominent exercise therapies (graded activity and motor control) for non-specific LBP.

The secondary aims include a cost-effectiveness analysis of a potential stratified care model.

Exploratory aims include the evaluation of potential new effect modifiers that may strengthen the initial prediction model. This include measures of central pain mechanisms to differentiate nociceptive, neuropathic and nociplastic pain.

Methods:

Participants (414) will be recruited by primary care professionals and will be randomized (1:1) to receive either motor control exercises or graded activity. Participants will receive 12 sessions of exercise therapy,delivered by a physiotherapist, over an 8-week period. The primary outcome will be disability at 2 months measured using the Oswestry Disability Index. Secondary outcomes will be pain, function and quality of life measured at 2, 6 and 12 months.

Potential effect modifiers will be the LSIQ, self-efficacy, coping strategies, kinesiophobia and measures of nociceptive pain and central sensitization. The study will follow specific guidelines for the conduction of effect modification studies.

Expected outcomes:

The results of this study will provide the foundation for the implementation of the study results in large scale which would significantly improve the effects of exercise for LBP. Furthermore, it will provide cost-effectiveness information to guide clinical decision making. Implementation of this approach would be simple as both treatments are already widely used and the method to identify subgroups of responders to each approach is straight forward, quick and at no cost.

Eligibility Criteria:
Inclusion Criteria:

* chronic non-specific LBP (\>3 months) with or without leg pain
* back pain being the primary musculoskeletal complaint of the patient
* between 18 to 80 years of age,
* English speaking (to allow response to questionnaires and communication with physiotherapist),
* moderate or greater pain or disability measured using question 7 and 8 of the SF-36,34
* moderate or high risk classification on the STarT Back Tool indicating appropriateness of physiotherapy and thus an exercise program.

Exclusion Criteria:

* nerve root compromise (2 strength, reflex or sensation affected for the same nerve root)
* suspected or confirmed serious pathology (e.g. infection, fracture, cancer, inflammatory arthritis, cauda equina syndrome)
* pregnancy
* scheduled or on the wait list for surgery during trial period
* cognitive impairment that precludes participant from completing study questionnaires or comply with exercise recommendations (e.g. dementia, Alzheimers)
* severe neuromuscular condition (e.g. spinal cord injury) that precludes participant from engaging in activity exercise.
* clinical assessment indicating that the participant is not suitable for active exercises (by a family physician, or using the Physical Activity Readiness Questionnaire).