............................................................................................................................................................................ Articles

Health Services Research
Spine. 32(21):2375-2378, October 1, 2007. Thiel, Haymo W. DC, PhD *; Bolton, Jennifer E. PhD *; Docherty, Sharon PhD *; Portlock, Jane C. PhD +

Abstract
Study Design. Prospective national survey.

Objective. To estimate the risk of serious and relatively minor adverse events following chiropractic manipulation of the cervical spine by a sample of U.K. chiropractors.

Summary of Background Data. The risk of a serious adverse event following chiropractic manipulation of the cervical spine is largely unknown. Estimates range from 1 in 200,000 to 1 in several million cervical spine manipulations.

Methods. We studied treatment outcomes obtained from 19,722 patients. Manipulation was defined as the application of a high-velocity/low amplitude or mechanically assisted thrust to the cervical spine. Serious adverse events, defined as "referred to hospital A&E and/or severe onset/worsening of symptoms immediately after treatment and/or resulted in persistent or significant disability/incapacity," and minor adverse events reported by patients as a worsening of presenting symptoms or onset of new symptoms, were recorded immediately, and up to 7 days, after treatment.

Results. Data were obtained from 28,807 treatment consultations and 50,276 cervical spine manipulations. There were no reports of serious adverse events. This translates to an estimated risk of a serious adverse event of, at worse [almost equal to]1 per 10,000 treatment consultations immediately after cervical spine manipulation, [almost equal to]2 per 10,000 treatment consultations up to 7 days after treatment and [almost equal to]6 per 100,000 cervical spine manipulations. Minor side effects with a possible neurologic involvement were more common. The highest risk immediately after treatment was fainting/dizziness/light-headedness in, at worse [almost equal to]16 per 1000 treatment consultations. Up to 7 days after treatment, these risks were headache in, at worse [almost equal to]4 per 100, numbness/tingling in upper limbs in, at worse [almost equal to]15 per 1000 and fainting/dizziness/light-headedness in, at worse [almost equal to]13 per 1000 treatment consultations.

Conclusion. Although minor side effects following cervical spine manipulation were relatively common, the risk of a serious adverse event, immediately or up to 7 days after treatment, was low to very low.