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Frequency and Clinical Predictors of Adverse Reactions to Chiropractic Care in the UCLA Neck Pain Study

Hurwitz, Eric L., DC, PhD*†; Morgenstern, Hal, PhD†‡; Vassilaki, Maria, MD, MPH*; Chiang, Lu-May, MS*

doi: 10.1097/01.brs.0000167821.39373.c1
Randomized Trial

Study Design. Randomized clinical trial.

Objectives. To document the types and frequencies of adverse reactions associated with the most common chiropractic treatments for neck pain, and to identify possible clinical predictors of adverse reactions to chiropractic treatment.

Summary of Background Data. Chiropractic care is frequently sought by patients for relief from neck pain; however, adverse reactions related to its primary modes of treatment have not been well examined.

Methods. A total of 336 patients with neck pain presenting to 4 southern California health care clinics were randomized in a balanced 2 × 2 × 2 factorial design to manipulation with or without heat, and with or without electrical muscle stimulation (EMS); and mobilization with or without heat and with or without EMS. Discomfort or unpleasant reactions from chiropractic care were self-assessed at 2 weeks after the randomization/baseline visit.

Results. Of the 280 participants (83%) who responded, 85 (30.4%) had 212 adverse symptoms as a result of chiropractic care. Increased neck pain or stiffness was the most common symptom, reported by 25% of the participants. Less common were headache and radiating pain. Patients randomized to manipulation were more likely than those randomized to mobilization to have an adverse symptom occurring within 24 hours of treatment (adjusted odds ratio [OR] = 1.44, 95% confidence interval [CI] = 0.83, 2.49). Heat and EMS were only weakly associated with adverse symptoms (heat: OR = 0.94, 95% CI = 0.54, 1.62; EMS: OR = 1.09, 95% CI = 0.63, 1.89). Moderate-to-severe neck disability at baseline was strongly associated with adverse neurologic symptoms (OR = 5.70, 95% CI = 1.49, 21.80).

Conclusions. Our results suggest that adverse reactions to chiropractic care for neck pain are common andthat despite somewhat imprecise estimation, adverse reactions appear more likely to follow cervical spine manipulation than mobilization. Given the possible higher risk of adverse reactions and lack of demonstrated effectiveness of manipulation over mobilization, chiropractors should consider a conservative approach for applying manipulation to their patients, especially those with severe neck pain.

Adverse reactions to chiropractic care for neck pain are common and appear more likely to follow cervical spine manipulation than mobilization. Mobilization rather than manipulation may be the more appropriate first-line therapy.

From the *Department of Epidemiology, UCLA School of Public Health, Los Angeles, CA, †Southern California University of Health Sciences, Whittier, CA, and ‡Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI.

Acknowledgment date: May 18, 2004. First revision date: July 16, 2004. Acceptance date: August 19, 2004.

Supported by grants from the Health Resources and Services Administration (R18 AH10008) and the National Chiropractic Mutual Insurance Company (NCMIC). Dr. Hurwitz was also supported by a grant from the National Center for Complementary and Alternative Medicine (K23 AT00055).

The manuscript submitted does not contain information about medical device(s)/drug(s).

Federal funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Eric L. Hurwitz, DC, PhD, Department of Epidemiology, UCLA School of Public Health, Box 951772, Los Angeles, CA 90095-1772; E-mail:

© 2005 Lippincott Williams & Wilkins, Inc.