Although empirical evidence suggests that chiropractic is a safe and effective means of natural healing, a growing body of scientific data supports the effectiveness of chiropractic. The studies listed below are a tiny fraction of the studies published on the efficacy of chiropractic.

The Rand Study -- The Rand Corporation, one of the most prestigious centers for research in public policy and health, released a study in 1991 which found that spinal manipulation is appropriate for specific kinds of low back pain.1

The Koes Clinical Trial -- A 1992 Dutch project compared manipulative therapy (chiropractic) and physiotherapy for the treatment of persistent back and neck complaints. After 12 months, the manipulative therapy group showed greater improvement in the primary complaint as well as in physical function, with fewer visits.2

The AHCPR Guideline -- In 1994, the Agency for Health Care Policy and Research (AHCPR), now the Agency on Health Research and Quality (AHRQ), an arm of the U.S. Department of Health and Human Services, released a clinical practice guideline for the treatment of acute low back problems. The guidelines recommend the use of spinal manipulation as an effective method of symptom control. The researches developing the guideline found that "manipulation...is safe and effective for patients in the first month of acute low back symptoms without radiculopathy [disease of the spinal nerve roots]".3

The Manga Study -- This study researched both the effectiveness and cost-effectiveness of the chiropractic management of low-back pain. Dr. Pran Manga, the study's author, found "on the evidence, particularly the most scientifically valid clinical studies, spinal manipulation applied by chiropractors is shown to be more effective than alternative treatment for LBP [Low-Back Pain]. Many medical therapies are of questionable validity or are clearly inadequate."4

The Duke Study -- Based on a literature review of several headache treatment options, a panel of 19 multidisciplinary experts concluded that spinal manipulation resulted in almost immediate improvement for cervicogenic headaches and had significantly fewer side effects and longer-lasting relief of tension-type headache than commonly-prescribed medication. Researchers concluded the following: "Manipulation appeared to result in immediate improvement in headache severity when used to treat episodes of cervicogenic headache when compared with and attention-placebo control. Furthermore, when compared to soft-tissue therapies (massage), a course of manipulation treatments resulted in sustained improvement in headache frequency and severity."5

The Boline Study -- This randomized controlled trial compared six weeks of spinal manipulative treatment of tension-type headache by chiropractors to six weeks of medical treatment with amitriptyline, a medication often prescribed for the treatment of severe tension headache pain. Researchers found that chiropractic patients experienced fewer side-effects (4.3%) than the amitriptyline group (82.1%) and while both were effective during the treatment phase of the study, only the chiropractic patients continued to report fewer headaches when treatment ended.6

The Nelson Migraine Study -- This study compared chiropractic spinal manipulation to amitriptyline ( a medication often prescribed for the treatment of headache) for the treatment of migraine headache. The researcher found that "Spinal manipulation seemed to be as effective as a well-established and efficacious treatment (amitriptyline). and on the basis of a benign side effects profile, it should be considered a treatment option for patients with frequent migraine headaches." The researchers also found that in weeks immediately following treatment, patients who had received spinal manipulation had a 42% reduction in headache frequency, compared to only 24% of those who took amitriptyline.7

The Colic Study -- When researchers compared spinal manipulation for the treatment of infantile colic to dimethicone ( a medication for colic), they came to a simple conclusion: "Spinal manipulation is effective in relieving infantile colic."8

References:

1. Shekelie PG, Adams, A, et al. The Appropriateness of Spinal Manipulation for Low-Back Pain: Indications and Ratings by a Multidisciplinary Expert Panel RAND Corporation, Santa Monica, California, 1991.
2. Koes BW, Bouter LM, et al. British Medical Journal March 7, 1992. Vol. 304, No 6827, pp. 601-605
3. Bigos S. Bowyer O, et al. Acute Low Back Problems in Adults. Clinical Practice Guideline, Number 14, Rockville, Maryland: U.S. Department of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research, AHCPR Pub. No 95-0642: December 1994.
4. Manga P. Angus D. et al. The Effectiveness and Cost-Effectiveness of Chiropractic Management of Low-Back Pain. The Ontario Ministry of Health, Ottawa, Ontario, Canada, August 1993.
5. McCrory DC. et al. Evidence Report: Behavioral and Physical Treatments for Tension-type and Cervicogenic Headache. Duke University Evidence-Based Practice Center, Durham, North Carolina, January 2001.
6. Boline PD, Kassak K. et al. Journal of Manipulative and Physiological Therapeutics. March/April 1995. Vol. 18, No. 3, pp. 148-154.
7. Nelson CF, et al. Journal of Manipulative and Physiological Therapeutics. October 1998, Vol. 21. No. 8, pp. 511-519.
8. Wilberg JMM, et al. Journal of Manipulative and Physiological Therapeutics. October 1999, Vol. 22 No. 8, pp. 517-522