Listings & Studies

Risk of Vertebrobasilar Stroke and Chiropractic Care:

Results of a Population-Based Case-Control and Case-Crossover Study.
Supplementary Research Studies


Study Design: Population-based, case-control and case-crossover study.

Objective: To investigate associations between chiropractic visits and vertebrobasilar artery (VBA) stroke and to contrast this with primary care physician (PCP) visits and VBA stroke.

Summary of Background Data: Chiropractic care is popular for neck pain and headache, but may increase the risk for VBA dissection and stroke. Neck pain and headache are common symptoms of VBA dissection, which commonly precedes VBA stroke.

Methods: Cases included eligible incident VBA strokes admitted to Ontario hospitals from April 1, 1993 to March 31, 2002. Four controls were age and gender matched to each case. Case and control exposures to chiropractors and PCPs were determined from health billing records in the year before the stroke date. In the case-crossover analysis, cases acted as their own controls.

Results: There were 818 VBA strokes hospitalized in a population of more than 100 million person-years. In those aged <45 years, cases were about three times more likely to see a chiropractor or a PCP before their stroke than controls. Results were similar in the case control and case crossover analyses. There was no increased association between chiropractic visits and VBA stroke in those older than 45 years. Positive associations were found between PCP visits and VBA stroke in all age groups. Practitioner visits billed for headache and neck complaints were highly associated with subsequent VBA stroke.

Conclusion: VBA stroke is a very rare event in the population. The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.

Safety of Chiropractic Manipulation of the Cervical Spine:

A Prospective National Survey.

Health Services Research


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.

Chronic Spinal Pain: A Randomized Clinical Trial Comparing Medication, Acupuncture, and Spinal Manipulation.

Randomized Trial

Spine. 28(14):1490-1502, July 15, 2003.
Giles, Lynton G. F. DC, PhD *+; Muller, Reinhold PhD +


Study Design: A randomized controlled clinical trial was conducted.

Objective: To compare medication, needle acupuncture, and spinal manipulation for managing chronic (>13 weeks duration) spinal pain because the value of medicinal and popular forms of alternative care for chronic spinal pain syndromes is uncertain.

Summary of Background Data: Between February 1999 and October 2001, 115 patients without contraindication for the three treatment regimens were enrolled at the public hospital’s multidisciplinary spinal pain unit.

Methods: One of three separate intervention protocols was used: medication, needle acupuncture, or chiropractic spinal manipulation. Patients were assessed before treatment by a sports medical physician for exclusion criteria and by a research assistant using the Oswestry Back Pain Disability Index (Oswestry), the Neck Disability Index (NDI), the Short-Form-36 Health Survey questionnaire (SF-36), visual analog scales (VAS) of pain intensity and ranges of movement. These instruments were administered again at 2, 5, and 9 weeks after the beginning of treatment.

Results: Randomization proved to be successful. The highest proportion of early (asymptomatic status) recovery was found for manipulation (27.3%), followed by acupuncture (9.4%) and medication (5%). Manipulation achieved the best overall results, with improvements of 50% (P = 0.01) on the Oswestry scale, 38% (P = 0.08) on the NDI, 47% (P < 0.001) on the SF-36, and 50% (P < 0.01) on the VAS for back pain, 38% (P < 0.001) for lumbar standing flexion, 20% (P < 0.001) for lumbar sitting flexion, 25% (P = 0.1) for cervical sitting flexion, and 18% (P = 0.02) for cervical sitting extension. However, on the VAS for neck pain, acupuncture showed a better result than manipulation (50%vs 42%).

Conclusions: The consistency of the results provides, despite some discussed shortcomings of this study, evidence that in patients with chronic spinal pain, manipulation, if not contraindicated, results in greater short-term improvement than acupuncture or medication. However, the data do not strongly support the use of only manipulation, only acupuncture, or only nonsteroidal antiinflammatory drugs for the treatment of chronic spinal pain. The results from this exploratory study need confirmation from future larger studies.