Context effects in LBP

Stimulated by Bishop et al 2021.[1]

LBP – low back pain
RCT – randomised controlled trial
RMDQ – Rowland Morris Disability Questionnaire
MCID – minimum clinically important difference

key to acronyms

I have been interested in context effects since Fabrizio Benedetti described the dramatic difference between open and closed administration of opioids in pain and the potential for conditioning placebo responses.[2] I was also surprised by his elaboration of target directed expectation,[3] and completely blown away by Ulrike Bingel’s demonstration of the power of nocebo in reversing the effects of intravenous remifentanil.[4]

Context effects may be particularly relevant in physical therapies including acupuncture since the effects in sham groups of RCTs appear large despite of our best attempts to minimise the specific effects of the intervention.

This is a very large pragmatic prospective observational cohort study investigating a variety of aspects of the treatment context in LBP within physiotherapy, osteopathy and acupuncture practice. 166 practitioners and 960 patients seeking treatment for LBP were recruited.

The primary outcome was back-related disability measured with the 24-item RMDQ.[5,6] The MCID for this measure in primary care has been calculated as 2-3 points. Secondary outcomes included pain intensity, well-being, work and social role disability, and satisfaction with care.

The contextual components assessed in the study were as follows:

  • Patient–practitioner relationship
  • The healthcare environment
  • Patients’ beliefs
  • Practitioners’ beliefs
  • Hypothesised mediators (constructs thought to be on the causal pathway between contextual components and patient outcomes – the perception of LBP as threatening; chronic pain self-efficacy; psychosocial distress)
  • Clinical and sociodemographic characteristics

Measures were applied at baseline, 2 weeks and 3 months. The 2-week questionnaires were completed by 767 patients and those at 3 months by 742. The latter figure was 108% of what had been expected.

The overall results show a drop of RMDQ by just over 3 points at 2 weeks and just over 4 points from baseline at 3 months. The drop was greatest for private physiotherapy and osteopathy, and smallest in the NHS physiotherapy cohort. The acupuncturist cohort was in between. It should be noted that acupuncture was used as a treatment in over 10% of physiotherapy and osteopathy encounters and only 60% of encounters with acupuncturists.

Manual therapy was provided in 60 to 70% of encounters with private physiotherapists (70.3%) and osteopaths (62.9%), but in only half as many encounters with NHS physiotherapists (31.1%) and acupuncturists (24.4%).

The main results of this study concern contextual predictors of back pain disability over time. These were calculated using multivariate regression, with effect sizes expressed using the partial eta-squared statistic. Using this statistic in multiple regression analyses 0.02 is a small effect, 0.13 a moderate effect, and 0.26 is a large effect.

therapeutic alliance (task)

practitioner beliefs about outcome

the biggest effects were seen for these contextual factors

The biggest effect (0.10) was found for therapeutic alliance (task), which effectively means the patient believes that the way the therapist is working with the problem is correct. This was measured at the two-week point. The next biggest effect (0.08) was for practitioner beliefs in terms of outcome expectancies, which corresponds to the degree to which the therapists thinks the course of treatment will be effective. This was measured at baseline.

Small but significant effects were measured for other aspects of the therapeutic alliance (goal and bond: 0.02 and 0.03 respectively), and for satisfaction with appointment systems (0.02) and the patient’s beliefs concerning the credibility of the treatment (0.01).

It is hard to imagine how we as therapists can maximise these effects beyond being as competent, attentive and considerate as we can. Those of us who work in large NHS organisations that have recently transitioned to fully computerised records and have a substantial waiting list following the restrictions of a pandemic may have additional challenges in maintaining satisfaction with the appointment system. But we can try!

Anyway, we are not currently allowed to treat people with acupuncture who present exclusively with LBP, so none of this applies to us just now. Of course, we live in hope that the nonsense of NG59 will eventually be reversed and in the meantime,  we can work on the backlog and appointments system.


1          Bishop F, Al-Abbadey M, Roberts L, et al. Direct and mediated effects of treatment context on low back pain outcome: a prospective cohort study. BMJ Open 2021;11:e044831. doi:10.1136/bmjopen-2020-044831

2          Amanzio M, Benedetti F. Neuropharmacological dissection of placebo analgesia: expectation-activated opioid systems versus conditioning-activated specific subsystems. J Neurosci 1999;19:484–94.

3          Benedetti F, Arduino C, Amanzio M. Somatotopic activation of opioid systems by target-directed expectations of analgesia. J Neurosci 1999;19:3639–48.

4          Bingel U, Wanigasekera V, Wiech K, et al. The effect of treatment expectation on drug efficacy: imaging the analgesic benefit of the opioid remifentanil. Sci Transl Med 2011;3:70ra14. doi:10.1126/scitranslmed.3001244

5          Roland M, Morris R. A study of the natural history of back pain. Part I: development of a reliable and sensitive measure of disability in low-back pain. Spine 1983;8:141–4. doi:10.1097/00007632-198303000-00004

6          Roland M, Morris R. A study of the natural history of low-back pain. Part II: development of guidelines for trials of treatment in primary care. Spine 1983;8:145–50. doi:10.1097/00007632-198303000-00005

Declaration of interests MC