Overall, there is little evidence in recent systematic reviews that SM is effective in any medical condition. We found 4 systematic reviews of SM for low back pain7-10
of which only one10
recommended its use. The remaining three systematic reviews,7-9
concluded that there was little evidence to support such advice. Ferreira7
concluded that SM is not substantially more effective than sham treatment for pain and no better than NSAIDs in improving disability in chronic back pain. The most recent, most comprehensive and most authoritative review9
states that SM or mobilization is superior to sham treatment and to detrimental or ineffective treatments but not better than other interventions for back pain.
Three systematic reviews were related to SM for neck pain10-12
of which one reached a a positive10
overall conclusion and this was the same review which reached a positive conclusion regarding back pain. The most authoritative of the three reviews12
stated that SM/mobilization is effective only when combined with other interventions such as exercise and as a sole treatment for neck pain, it is not of demonstrable effectiveness.
Similarly, there are three systematic reviews of SM for headache.13-15
While Bronfort et al
concluded that SM is as effective as other interventions, the other two teams of reviewers14,15
did not find conclusive evidence in favour of SM.
The evidence from the other systematic reviews of SM for non-spinal pain,16
cervicogenic dizziness and any condition21
is uniformly negative.
Overall, the demonstrable benefit of SM seems to be minimal in the case of acute or chronic back pain; controversial in the case of headache; or absent for all other indications. Other interventions, e.g. exercise therapy, may therefore be preferable.23-25
We do, however, note that the absence of evidence is not the same as evidence of absence of an effect. None of the reviews conclusively demonstrates that SM is ineffective.
All systematic reviews are prone to publication bias within the primary research data which they include and because our study is a systematic review of systematic reviews, any such bias may have been inherited in our study. In our view, such effects would have tended to favour SM. Our own search strategy was thorough, and although we cannot be absolutely sure that all relevant systematic reviews were located, we believe that publication bias is likely to have been less of a problem in identifying systematic reviews than in identifying all relevant clinical trials. Our previous work6
has shown that the conclusions of reviews of SM for back pain appear to be influenced by authorship and methodological quality such that authorship by osteopaths or chiropractors and low methodological quality are associated with a positive conclusion. It is perhaps relevant to note that all three of the overtly positive recommendations for SM in the indications back pain,10
originate from the same chiropractor. Ernst and/or Canter, the present authors, conducted three of the systematic reviews included8,11,16
and all three reviews reached negative conclusions about the effectiveness of spinal manipulation. However, these systematic reviews were themselves carried out in a rigorous and systematic fashion and we therefore do not believe that their inclusion represents a source of any additional bias.
We do not have other systematic reviews of systematic reviews of spinal manipulation with which to compare our conclusions, but they are consistent with the conclusions of 13 of the 16 most recent systematic reviews.
Spinal manipulation has been associated with frequent, mild adverse effects26
and with serious (probably) rare complications.27
Therefore the risk-benefit balance does not favour SM over other treatment options such as physiotherapeutic exercise. This statement is not in agreement with several national guidelines, for instance, for the treatment of back pain.28-30
We suggest that these guidelines be reconsidered in the light of the best available data.
In conclusion, we have found no convincing evidence from systematic reviews to suggest that SM is a recommendable treatment option for any medical condition. In several areas, where there is a paucity of primary data, more rigorous clinical trials could advance our knowledge.