An examination of the observed placebo effect associated with the treatment of low back pain - A systematic review

Canadian Memorial Chiropractic College, Toronto, Ontario, Canada.
Pain research & management: the journal of the Canadian Pain Society = journal de la societe canadienne pour le traitement de la douleur (Impact Factor: 1.52). 01/2011; 16(1):45-52.
Source: PubMed


To determine whether the nonspecific effects that occur following the use of sham interventions to treat nonspecific low back pain (LBP) are large enough to be considered clinically meaningful.
Electronic databases were searched systematically for randomized placebo-controlled trials of interventions for LBP that used sham ultrasound, sham laser or sham drug therapy as the placebo control. Study selection was accomplished via independent evaluation of scientific admissibility by three reviewers and final decisions of inclusion were based on consensus.
None of the studies using sham ultrasound as the placebo control in the treatment of LBP were acceptable for inclusion. Twelve studies were included in the present evaluation of the placebo effect - eight trials that met the strict inclusion criteria for best evidence (three using sham laser placebo and five using sham medication placebo) and four sham medication studies that 'just missed' the inclusion criteria for best evidence. Although the evidence from studies using sham laser was inconclusive, the present review did find a clinically meaningful change in LBP scores following the use of sham oral medications.
The present best-evidence review found a clinically meaningful change in pain scores following the use of sham oral medications for the treatment of nonspecific LBP. This finding suggests that further clinical research is warranted to identify which patient subgroups could benefit most from such treatment and to distinguish the true contribution of the placebo effect from other nonspecific effects.

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Available from: Aaron A Puhl,
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    • "This may enable the current study findings to be comparable with other spinal manipulative therapies to lumbar spine while conducting systematic reviews. A recent systematic review suggested that meaningful change in pain scores in low back pain might be influenced by placebo or sham interventional effects (Puhl et al., 2011). Although VAS and ODI are relevant tools in this study, both these tools may be relatively subjective in nature. "
    Journal of bodywork and movement therapies 10/2012; 16(4):409-10. DOI:10.1016/j.jbmt.2012.01.001
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    • "This problem is not confined to spinal manipulation as a therapy nor is it confined to treatments for the neck alone. Machado et al. [11] and Puhl et al. [42] have shown that the same problem exists for other pharmacologic and non-pharmacologic treatments for low back pain. "
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    ABSTRACT: To characterize the types of control procedures used in controlled clinical trials of cervical spine manipulation and to evaluate the outcomes obtained by subjects in control groups so as to improve the quality of future clinical trials A search of relevant clinical trials was performed in PubMed 1966-May 2010 with the following key words: "Chiropractic"[Mesh] OR "Manipulation, Spinal"[Mesh]) AND "Clinical Trial "[Publication Type]. Reference lists from these trials were searched for any additional trials. The reference lists of two prior studies, one review and one original study were also searched. Accepted reports were then rated for quality by 2 reviewers using the PEDro scale. Studies achieving a score of >50% were included for data extraction and analysis. Intra-group change scores on pain outcomes were obtained. For determining clinically important outcomes, a threshold of 20% improvement was used where continuous data were available; otherwise, an effect size of 0.30 was employed The PubMed search yielded 753 citations of which 13 were selected. Eight (8) other studies were identified by reviewing two systematic reviews and through reference searches. All studies scored >50% on the PEDro scale. There were 9 multi-session studies and 12 single-session studies. The most commonly used control procedure was "manual contact/no thrust". Four (4) studies used a placebo-control (patient blinded). For two of these studies with VAS data, the average change reported was 4.5 mm. For the other control procedures, variable results were obtained. No clinically important changes were reported in 57% of the paired comparisons, while, in 43% of these, changes which would be considered clinically important were obtained in the control groups. Only 15% of trials reported on post-intervention group registration. Most control procedures in cervical manipulation trials result in small clinical changes, although larger changes are observed in 47% of paired comparisons. The vast majority of studies do not result in subject blinding; the effect of unmasking of control subjects in these studies makes the interpretation of the existing clinical trials challenging. The greatest majority of trials do not report on post-intervention blinding. A small number of candidate procedures for effective control interventions exist. Much more research is required to improve this important aspect of clinical trial methodology in cervical manipulation studies.
    Chiropractic and Manual Therapies 01/2011; 19(1):3. DOI:10.1186/2045-709X-19-3
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    ABSTRACT: Various studies have shown that spine stabilisation exercise therapy elicits improvements in symptoms/disability in patients with chronic non-specific low back pain (cLBP). However, few have corroborated the intended mechanism of action by examining whether clinical improvements (1) are greater in patients with functional deficits of the targeted muscles and (2) correlate with post-treatment improvements in abdominal muscle function. Pre and directly after 9 weeks' therapy, 32 cLBP patients (44.0 ± 12.3 years) rated their LBP intensity (0-10) and disability (0-24, Roland-Morris; RM) and completed psychological questionnaires. At the same timepoints, the voluntary activation of transversus abdominis (TrA), obliquus internus and obliquus externus during "abdominal-hollowing" and the anticipatory ("feedforward") activation of these muscles during rapid arm movements were measured using M-mode ultrasound with tissue Doppler imaging. Pre-therapy to post-therapy, RM decreased from 8.9 ± 4.7 to 6.7 ± 4.3, and average pain, from 4.7 ± 1.7 to 3.5 ± 2.3 (each P < 0.01). The ability to voluntarily activate TrA increased by 4.5% (P = 0.045) whilst the anticipatory activation of the lateral abdominal muscles showed no significant change (P > 0.05). There was no significant correlation between the change in RM scores after therapy and either baseline values for voluntary (r = 0.24, P = 0.20) or anticipatory activation (r = 0.04, P = 0.84), or their changes after therapy (voluntary, r = 0.08, P = 0.66; anticipatory, r = 0.16, P = 0.40). In multiple regression, only a reduction in catastrophising (P = 0.0003) and in fingertip-floor distance (P = 0.0006) made unique contributions to explaining the variance in the reduction in RM scores. Neither baseline lateral abdominal muscle function nor its improvement after a programme of stabilisation exercises was a statistical predictor of a good clinical outcome. It is hence difficult to attribute the therapeutic result to any specific effects of the exercises on these trunk muscles. The association between changes in catastrophising and outcome serves to encourage further investigation on larger groups of patients to clarify whether stabilisation exercises have some sort of "central" effect, unrelated to abdominal muscle function per se.
    European Spine Journal 01/2012; 21(7):1301-10. DOI:10.1007/s00586-012-2155-9 · 2.07 Impact Factor
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