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Adverse events and cervical manipulation for neck pain

PainSci » bibliography » Carlesso et al 2010
Tags: neck, spinal adjustment, chiropractic, controversy, head/neck, spine, modalities, manual therapy, treatment, debunkery

Four articles on PainSci cite Carlesso 2010: 1. The Complete Guide to Chronic Tension Headaches2. The Complete Guide to Neck Pain & Cricks3. What Happened To My Barber?4. Does Spinal Manipulation Work?

PainSci commentary on Carlesso 2010: ?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

This study analysed the scientific literature looking for evidence of harm from spinal manipulative therapy (SMT) in the neck, and found a statistically insignificant trend towards the negative, an uncertain number that leaned in the direction of bad news: increased neck pain might be 25% more likely with SMT than if you did nothing, or if you just stuck to safe and neutral treatments. The same murky data could also suggest basically the opposite: the absence of a clear signal constitutes “strong evidence that neck manipulation or mobilization does not result in an increase in neck pain,” according to the authors. Debatable, but noted. (There are just too many ways the data could be missing the truth entirely here. And this is acknowledged in the paper, practically in the next sentence: “However, the limitations of the Strunk study and the low GRADE rating remain, affecting confidence in the estimate.”)

What about non-pain symptoms? More spectacularly, patients are 100% more likely to have “transient neurological symptoms” (which can range from dizziness all the way up to serious unpleasantness, such as severe dizziness, nausea and vomiting, as described in What Happened To My Barber?). (These are relative risk measurements: the risk compared to not getting treated — not the overall likelihood, which cannot be measured from this kind of data.)

And how about injury or death? The authors could not calculate the relative risk from this evidence. Here be statistical dragons. At first glance this might seem to indicate that such serious harm is unlikely — wouldn’t a problem show up if it were serious? Only if the research was actually designed to detect it. These authors were simply going through data from many small studies of neck adjustment, in which some rotten reactions were noted (while many other studies were disqualified for not tracking harms at all). It remains entirely possible that the phenomenon is real but rare, and simply didn’t occur, or wasn’t noted, in any of the studies considered here. Similarly, you could analyze dozens of studies of the health effects of hiking, but probably none of them would have data about bear attacks — yet bears do attack people!

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

Adverse events (AE) are a concern for practitioners utilizing cervical manipulation or mobilization. While efficacious, these techniques are associated with rare but serious adverse events. Five bibliographic databases (PubMed, CINAHL, PEDro, AMED, EMBASE) and the gray literature were searched from 1998 to 2009 for any AE associated with cervical manipulation or mobilization for neck pain. Randomized controlled trials (RCTs), prospective or cross-sectional observational studies were included. Two independent reviewers conducted study selection, method quality assessment and data abstraction. Pooled relative risks (RR) were calculated. Study quality was assessed using the Cochrane system, a modified Critical Appraisal Skills Program form and the McHarm scale to assess the reporting of harms. Seventeen of 76 identified citations resulted in no major AE. Two pooled estimates for minor AE found transient neurological symptoms [RR 1.96 (95% CI: 1.09-3.54) p<0.05]; and increased neck pain [RR 1.23 (95% CI: 0.85-1.77) p>.05]. Forty-four studies (58%) were excluded for not reporting AE. No definitive conclusions can be made due to a small number of studies, weak association, moderate study quality, and notable ascertainment bias. Improved reporting of AE in manual therapy trials as recommended by the CONSORT statement extension on harms reporting is warranted.

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