Reporting of adverse effects in randomised clinical trials of chiropractic manipulations: a systematic review

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.