New evidence on adverse effects of manual therapy comes from an unexpected source. Here is the abstract of the paper:
The aim of this study was to investigate if mild or moderate adverse events after manual therapy has an impact on the chance to recover from back/neck pain in men and women. A prospective cohort study of 771 patients with at least three treatment sessions in a randomized controlled trial performed in January 2010 – December 2013. Adverse events within 24 h after each treatment were measured with questionnaires and categorized as: no, mild or moderate, based on bothersomeness. Outcome measure was the perceived recovery at seven weeks and at three months follow-up. Odds Ratios (OR) and 95% confidence intervals (CI) were calculated by Logistic regression to investigate the associations between the exposure and outcome, and to test and adjust for potential confounding. There were no statistically significant associations observed between the experience of mild or moderate adverse events and being recovered at the seven weeks follow-up. The only statistically significant association observed at the three months follow-up was for mild adverse events in men with an OR of 2.44, 95% CI: 1.24–4.80 in comparison to men with no adverse events. This study indicates that mild adverse events after manual therapy may be related to a better chance to recover in men.
In my view this is a rather boring analysis of a bizarre hypothesis … were it not for a result that cropped up almost unintendedly: AE were reported in 81% of women and 66% of men. No severe irreversible AE were reported, but 178 AEs were rated as moderate to severe. As only symptoms within 24 h after the first three treatment session were reported, the true figures might even be larger.
These figures are considerably higher than previously reported. Our own systematic review of prospective studies suggested that AEs occur in approximately half of all patients receiving spinal manipulation. It follows, I think, that we have to discuss the question about risk versus benefit of manual treatments (such as spinal manipulations) even more critically than before.