Study design: Systematic review of reported adverse events.
Objective: To evaluate the tolerability and safety of chiropractic procedures.
Summary of background data: Despite the increasing popularity of chiropractic, there are few properly designed prospective controlled trials, and there is a disproportionate lack of evaluation of its safety profile. The literature reports multiple neurologic complications of spinal manipulation, some of which are clinically relevant and even life threatening.
Methods: We performed an electronic search in 2 databases: Pubmed and the Cochrane Library for the years 1966 to 2007. All articles that reported adverse reactions associated with chiropractic were included irrespective of type of design. The outcome measures were the type of adverse events associated or attributed to chiropractic interventions and their frequency.
Results: A total of 376 potential relevant articles were identified, 330 of which were discarded after abstract or complete article analysis. The search identified 46 articles that included data concerning adverse events: 1 randomized controlled trial, 2 case-control studies, 7 prospective studies, 12 surveys, 3 retrospective studies, and 115 case reports. Most of the adverse events reported were benign and transitory, however, there are reports of complications that were life threatening, such as arterial dissection, myelopathy, vertebral disc extrusion, and epidural hematoma. The frequency of adverse events varied between 33% and 60.9%, and the frequency of serious adverse events varied between 5 strokes/100,000 manipulations to 1.46 serious adverse events/10,000,000 manipulations and 2.68 deaths/10,000,000 manipulations.
Conclusion: There is no robust data concerning the incidence or prevalence of adverse reactions after chiropractic. Further investigations are urgently needed to assess definite conclusions regarding this issue.