This systematic review was aimed at determining if there has been a change in the reporting of adverse events associated with spinal manipulation in randomized clinical trials (RCTs) since 2016.
Databases were searched from March 2016 to May 2022: MEDLINE (Ovid), Embase, CINAHL, ICL, PEDro, and Cochrane Library. The following search terms and their derivatives were adapted for each platform: spinal manipulation; chiropractic; osteopathy; physiotherapy; naprapathy; medical manipulation and clinical trial.
Domains of interest (pertaining to adverse events) included: completeness and location of reporting; nomenclature and description; spinal location and practitioner delivering manipulation; methodological quality of the studies and details of the publishing journal. Frequencies and proportions of studies reporting on each of these domains were calculated. Univariable and multivariable logistic regression models were fitted to examine the effect of potential predictors on the likelihood of studies reporting on adverse events.
There were 5399 records identified by the electronic searches, of which 154 (2.9%) were included in the analysis. Of these, 94 (61.0%) reported adverse events with only 23.4% providing an explicit description of what constituted an adverse event. Reporting of adverse events in the abstract had increased (n=29, 30.9%) while reporting in the results section had decreased (n=83, 88.3%) over the past 6 years. Spinal manipulation was delivered to 7518 participants in the included studies. No serious adverse events were reported in any of these studies.
The authors concluded that, while the current level of reporting of adverse events associated with spinal manipulation in RCTs has increased since our 2016 publication on the same topic, the level remains low and inconsistent with established standards. As such, it is imperative for authors, journal editors and administrators of clinical trial registries to ensure there is more balanced reporting of both benefits and harms in RCTs involving spinal manipulation.
In fact, it is an ethical imperative to accurately report adverse effects. Not reporting adverse effects amounts to a violation of medical research ethics. Adverse effects of spinal manipulation occur in about 50% of all patients. This means that investigators reporting significantly lower figures are likely guilty of under-reporting. And under-reporting of adverse events is also a breach of ethical standards.
My conclusion thus is that the vast majority of trials of spinal manipulation are unethical and should be discarded.