Trial Protocol: Cognitive functional therapy compared with combined manual therapy and motor control exercise for people with non-specific chronic low back pain: protocol for a randomised, controlled trial

Introduction: Chronic low back pain is a public health problem, and there is strong evidence that it is associated with a complex interaction of biopsychosocial factors. Cognitive functional therapy is an intervention that deals with potentially modifiable multidimensional aspects of pain (eg, provocative cognitive, movement and lifestyle behaviours). There is evidence (from a single randomised, controlled trial) that cognitive functional therapy is better than combined manual therapy and motor control exercise. However, this study had significant methodological shortcomings including the failure to carry out an intention-to-treat analysis and a considerable loss of follow-up of participants. It is important to replicate this study in another domain through a randomised clinical trial with similar objectives but correcting these methodological shortcomings.

Aim: To investigate the efficacy of cognitive functional therapy compared to combined manual therapy and exercise on pain and disability at 3 months in patients with chronic non-specific low back pain.

Design: Two-group, randomised, multicentre controlled trial with blinded assessors.

Participants and settings: One hundred and forty-eight participants with chronic low back pain that has persisted for >3months and no specific spinal pathology will be recruited from the school clinic of the Centro Universitário Augusto Motta and a private clinic in the city of Rio de Janeiro, Brazil.

Intervention a: Four to 10 sessions of cognitive functional therapy. The physiotherapists who will treat the participants in the cognitive functional therapy group have previously attended 2 workshops with two different tutors of the method. Such physiotherapists have completed 106 hours of training, including workshops and patient examinations, as well as conducting a pilot study under the supervision of another physiotherapist with>3 years of clinical experience in cognitive functional therapy.

Intervention b: Four to 10 sessions of combined manual therapy and motor control exercises. Participants in the combined manual therapy and exercise group will be treated by two physiotherapists with an average of >10years of clinical experience in manual therapy and motor control exercises, including isolated contractions of the deep abdominal muscles.

Measurements: The primary outcome measures will be pain intensity and disability 3 months after randomisation. Secondary outcomes will be pain and disability assessed 6 and 12 months after randomisation, and both global perceived effect and patient satisfaction at 3, 6 and 12 months after randomisation. The potential outcome mediators will be assessed at 3 and 6 months after randomisation, with brief screening questions for anxiety, social isolation, catastrophisation, depression, fear of movement, stress and sleep. Non-specific predictors and moderators will include age, gender, duration of chronic low back pain, chronicity risk (Örebro and Start Back score), number of pain areas, stressful life event, MRI scan imaging, and family history.

Analysis: Intention-to-treat analysis will be performed. Linear mixed models will be used to compare the mean differences in pain intensity, disability and global perceived effect between the intervention arms. The analysis of the effect of potential mediators of the treatment will be performed using the causal mediation methods described by Imai and colleagues. The baseline variables will be evaluated as predictors and moderators of treatment, including terms and interaction models. A level of statistical significance of 5% will be used in the analysis. All the analyses will be performed using RStudio.

Significance: This study will investigate whether the results of the first cognitive functional therapy randomised clinical trial are reproducible. The present study will have a sample size capable of detecting clinically relevant effects of the treatment with a low risk of bias. In pragmatic terms, this clinical trial is designed to reproduce the intervention as it would be performed in clinical practice by a trained physiotherapist who works with cognitive functional therapy, which increases the relevance of this study. The combined manual therapy and exercise group comprises an intervention strategy widely used by physiotherapists to treat low back pain. As evidence of efficacy is still limited, the results of a randomised, controlled clinical trial of high methodological quality will help physiotherapists in clinical decision-making.