Due to the unclear risk level of adverse events (AEs) associated with high-velocity, low-amplitude (HVLA) cervical manipulation, the aim of this study was to extract available information from randomized clinical trials (RCTs) and thereby synthesize the comparative risk of AEs following cervical manipulation to that of various control interventions.

 A systematic literature search was conducted in the PubMed and Cochrane databases. This search included RCTs in which cervical HVLA manipulations were applied and AEs were reported. Two independent reviewers performed the study selection, the methodological quality assessment, and the GRADE approach. Incidence rate ratios (IRR) were calculated. The study quality was assessed by using the risk of bias 2 (RoB-2) tool, and the certainty of evidence was determined by using the GRADE approach.

Fourteen articles were included in the systematic review and meta-analysis. The pooled IRR indicates no statistically significant differences between the manipulation and control groups. All the reported AEs were classified as mild, and none of the AEs reported were serious or moderate.

The authors concluded that HVLA manipulation does not impose an increased risk of mild or moderate AEs compared to various control interventions. However, these results must be interpreted with caution, since RCTs are not appropriate for detecting the rare serious AEs. In addition, future RCTs should follow a standardized protocol for reporting AEs in clinical trials.

I am more than a little puzzled by this paper. To explain why, I best show you our systematic review of a closely related subject:

Objective: To systematically review the reporting of adverse effects in clinical trials of chiropractic manipulation.

Data sources: Six databases were searched from 2000 to July 2011. Randomised clinical trials (RCTs) were considered, if they tested chiropractic manipulations against any control intervention in human patients suffering from any type of clinical condition. The selection of studies, data extraction, and validation were performed independently by two reviewers.

Results: Sixty RCTs had been published. Twenty-nine RCTs did not mention adverse effects at all. Sixteen RCTs reported that no adverse effects had occurred. Complete information on incidence, severity, duration, frequency and method of reporting of adverse effects was included in only one RCT. Conflicts of interests were not mentioned by the majority of authors.

Conclusions: Adverse effects are poorly reported in recent RCTs of chiropractic manipulations.

So, AEs are known to get seriously (and unethically) neglected in RCTs of chiropractic. Therefore, it must be expected that the new review finds only few of them in RCTs. No big deal! But why then conclude that HVLA manipulations do not impose an increased risk? Why do the authors claim that “case reports … do not imply causal relationships”? Why not be honest and simply state that RCTs are an inadequate tool for assessing the risks of spinal manipulation? And why ignore our review which, after all, is highly relevant and was published in a most visible journal? Did they perhaps read it and then decided to ignore it because it would have rendered their whole approach idiotic?

I don’t know the answer to any of these questions. What I do know, however, is that this new review arrives at a utterly misleading and possibly harmful conclusion. It thus is a significant disservice to our need to making progress in this important area.

11 Responses to Adverse Events After Cervical Spinal Manipulation: a new (and most surprising) review

  • i am sorry prof. it appears you had a slight misunderstanding… the cautious authors did not say “AE are neglected in chiropractic RCT” they did say RCT in general are not the best of tools to asses AE of any technique… by the way where did you find “chiropractic” mentioned anywhere in this analysis???

    if you claim to support evidence based practice you need to accept the evidence even when it goes against your agenda… i am sure we can agree on that

    • “they did say RCT in general are not the best of tools to asses AE of any technique”
      they did say: “RCTs are not appropriate for detecting the rare SERIOUS AEs.” [an important difference]
      “did you find “chiropractic” mentioned anywhere in this analysis?”
      “if you claim to support evidence based practice you need to accept the evidence even when it goes against your agenda… i am sure we can agree on that”

  • I could answer most of those questions but let me get to the point.

    RCT aren’t necessarily mirroring what is occurring in the global clinical practice of cSMT.

    Inotherwords, most of the cases of serious AE that we read about that are associated with cSMT, those cases most likely would have been excluded from a RCT due to contraindications to cSMT.

    It’s not a procedure problem per se, it’s a practitioner problem. And that could be solved, hopefully, with education.

  • Practitioner problem?
    I think not.

    The only appropriate “education” would be to instruct Chiropractors to STOP doing rapid upper neck manipulations.

    • well David, the findings regarding case studies is that most serious AE were likely due to “missed” contraindications. That is a practitioner problem. Some are due to improper technique, that is a practitioner problem. Other studies have found that it is the other professions, DO, PT and MD that report the highest percentage/utilization of serious AE. So, if you really want to address the main issue it would be to get DO, PT and MDs to stop doing cSMT as they are the most likely ones to hurt someone doing cSMT (at least based on published papers). Could it be that they also have the least training on the subject?

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