The question whether spinal manipulation is an effective treatment for infant colic has attracted much attention in recent years. The main reason for this is, of course, that a few years ago Simon Singh had disclosed in a comment that the British Chiropractic Association (BCA) was promoting chiropractic treatment for this and several other childhood condition on their website. Simon famously wrote “they (the BCA) happily promote bogus treatments” and was subsequently sued for libel by the BCA. Eventually, the BCA lost the libel action as well as lots of money, and the entire chiropractic profession ended up with enough egg on their faces to cook omelets for all their patients.
At the time, the BCA had taken advice from several medical and legal experts; one of their medical advisers, I was told, was Prof George Lewith. Intriguingly, he and several others have just published a Cochrane review of manipulative therapies for infant colic. Here are the unabbreviated conclusions from their article:
“The studies included in this meta-analysis were generally small and methodologically prone to bias, which makes it impossible to arrive at a definitive conclusion about the effectiveness of manipulative therapies for infantile colic. The majority of the included trials appeared to indicate that the parents of infants receiving manipulative therapies reported fewer hours crying per day than parents whose infants did not, based on contemporaneous crying diaries, and this difference was statistically significant. The trials also indicate that a greater proportion of those parents reported improvements that were clinically significant. However, most studies had a high risk of performance bias due to the fact that the assessors (parents) were not blind to who had received the intervention. When combining only those trials with a low risk of such performance bias, the results did not reach statistical significance. Further research is required where those assessing the treatment outcomes do not know whether or not the infant has received a manipulative therapy. There are inadequate data to reach any definitive conclusions about the safety of these interventions”
Cochrane reviews also carry a “plain language” summary which might be easier to understand for lay people. And here are the conclusions from this section of the review:
The studies involved too few participants and were of insufficient quality to draw confident conclusions about the usefulness and safety of manipulative therapies. Although five of the six trials suggested crying is reduced by treatment with manipulative therapies, there was no evidence of manipulative therapies improving infant colic when we only included studies where the parents did not know if their child had received the treatment or not. No adverse effects were found, but they were only evaluated in one of the six studies.
If we read it carefully, this article seems to confirm that there is no reliable evidence to suggest that manipulative therapies are effective for infant colic. In the analyses, the positive effect disappears, if the parents are properly blinded; thus it is due to expectation or placebo. The studies that seem to show a positive effect are false positive, and spinal manipulation is, in fact, not effective.
The analyses disclose another intriguing aspect: most trials failed to mention adverse effects. This confirms the findings of our own investigation and amounts to a remarkable breach of publication ethics (nobody seems to be astonished by this fact; is it normal that chiropractic researchers ignore generally accepted rules of ethics?). It also reflects badly on the ability of the investigators of the primary studies to be objective. They seem to aim at demonstrating only the positive effects of their intervention; science is, however, not about confirming the researchers’ prejudices, it is about testing hypotheses.
The most remarkable thing about the new Cochrane review is, I think, the in-congruence of the actual results and the authors’ conclusion. To a critical observer, the former are clearly negative but the latter sound almost positive. I think this begs the question about the possibility of reviewer bias.
We have recently discussed on this blog whether reviews by one single author are necessarily biased. The new Cochrane review has 6 authors, and it seems to me that its conclusions are considerably more biased than my single-author review of chiropractic spinal manipulation for infant colic; in 2009, I concluded simply that “the claim [of effectiveness] is not based on convincing data from rigorous clinical trials”.
Which of the two conclusions describe the facts more helpfully and more accurately?
I think, I rest my case.