The objective of this systematic review was to assess the effects and reliability of sham procedures in manual therapy (MT) trials in the treatment of back pain (BP) in order to provide methodological guidance for clinical trial development. Different databases were screened up to 20 August 2020. Randomised clinical trials involving adults affected by BP (cervical and lumbar), acute or chronic, were included. Hand contact sham treatment (ST) was compared with different MT (physiotherapy, chiropractic, osteopathy, massage, kinesiology, and reflexology) and to no treatment. Primary outcomes were BP improvement, the success of blinding, and adverse effect (AE). Secondary outcomes were the number of drop-outs. Dichotomous outcomes were analysed using risk ratio (RR), continuous using mean difference (MD), 95% CIs. The minimal clinically important difference was 30 mm changes in pain score.
A total of 24 trials were included involving 2019 participants. Different manual treatments were provided:
- SM/chiropractic (7 studies, 567 participants).
- Osteopathy (5 trials, 645 participants).
- Kinesiology (1 trial, 58 participants).
- Articular mobilisations (6 trials, 445 participants).
- Muscular release (5 trials, 304 participants).
Very low evidence quality suggests clinically insignificant pain improvement in favour of MT compared with ST (MD 3.86, 95% CI 3.29 to 4.43) and no differences between ST and no treatment (MD -5.84, 95% CI -20.46 to 8.78).ST reliability shows a high percentage of correct detection by participants (ranged from 46.7% to 83.5%), spinal manipulation being the most recognised technique. Low quality of evidence suggests that AE and drop-out rates were similar between ST and MT (RR AE=0.84, 95% CI 0.55 to 1.28, RR drop-outs=0.98, 95% CI 0.77 to 1.25). A similar drop-out rate was reported for no treatment (RR=0.82, 95% 0.43 to 1.55).
Forest plot of comparison ST versus MT in back pain outcome at short term. MT, manual therapy; ST, sham treatment.
The authors concluded that MT does not seem to have clinically relevant effect compared with ST. Similar effects were found with no treatment. The heterogeneousness of sham MT studies and the very low quality of evidence render uncertain these review findings. Future trials should develop reliable kinds of ST, similar to active treatment, to ensure participant blinding and to guarantee a proper sample size for the reliable detection of clinically meaningful treatment effects.
Essentially these findings suggest that the effects patients experience after MT are not due to MT per see but to placebo effects. The review could be criticised because of the somewhat odd mix of MTs lumped together in one analysis. Yet, I think it is fair to point out that most of the studies were of chiropractic and osteopathy. Thus, this review implies that chiropractic and osteopathy are essentially placebo treatments.
The authors of the review also provide this further comment:
Similar findings were found in other reviews conducted on LBP. Ruddock et al included studies where SM was compared with what authors called ‘an effective ST’, namely a credible sham manipulation that physically mimics the SM. Pooled data from four trials showed a very small and not clinically meaningful effect in favour of MT.52
Rubinstein et al 53 compared SM and mobilisation techniques to recommended, non-recommended therapies and to ST. Their findings showed that 5/47 studies included attempted to blind patients to the assigned intervention by providing an ST. Of these five trials, two were judged at unclear risk of participants blinding. The authors also questioned the need for additional studies on this argument, as during the update of their review they found recent small pragmatic studies with high risk of bias. We agree with Rubinstein et al that recent studies included in this review did not show a higher quality of evidence. The development of RCT with similar characteristic will probably not add any proof of evidence on MT and ST effectiveness.53
If we agree that chiropractic and osteopathy are placebo therapies, we might ask whether they should have a place in the management of BP. Considering the considerable risks associated with them, I feel that the answer is obvious and simple: