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FCER Research Release

VAD Following Cervical Manipulation: 
D.C. vs M.D. Experiences Affect Perception of Risk

January 13, 2003

 Contact: Robin R. Merrifield

1304 Perry Ave., Bremerton WA 98310

Phone: 800-343-0549 or 360-478-2716

Fax: 360-478-0834 E-Mail:

Des Moines, Iowa ó Ask a Doctor of Chiropractic and a neurologist what a patientís risk of stroke following cervical manipulation is and the answers given will likely differ greatly. Chiropractic estimates are at approximately 0.2 per million adjustments, whereas medical literature has the risk at about 1 per 500,000 adjustments.

In an effort to examine the role of bias in these estimations, Scott Haldeman, D.C., M.D., Ph.D., and Paul Carey, D.C., Murray Townsend, D.C, and Costa Papadopoulos, MHA, CHE, studied the perceived incidence of vertebral artery dissection (VAD) from both the chiropractic and neurologist points of view.

Examination of the database of the Canadian Chiropractic Protective Association (CCPA, which provides malpractice insurance for 85% of chiropractors in Canada) for the period 1988 to 1997 found 23 cases of VAD. Retrospective review of these cases and a survey of chiropractors suggests an estimated 134,466,765 cervical manipulations were performed during the 10-year period. Records from these reported VAD cases indicates that in a 30 year practice, only one in 48 chiropractors would be aware of a vascular incident following cervical manipulation. In contrast, examination of the records show that these 23 VAD patients saw a total of 216 physicians, including 69 neurologists.

The researchers concluded that "the difference in the number of chiropractors . . . and neurologists . . . in active practice and the fact that each patient who has a stroke following manipulation will likely be seen by only one chiropractor but by 3 or more neurologists partly explains the difference in experience and the perception of risk of these two professions. This selection or referral bias is important in shaping the clinical opinions of the various disciplines and distorts discussion on the true incidence of these complications of cervical manipulation."

It is important to note that this study was not an attempt to define the risk of stroke following manipulation. Rather it is an examination of the differences in perception.

The study was published in The Spine Journal, September 2002. Reprints of the full article may be requested from Paul Carey, D.C., at or fax a request to (519) 273-4161.

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