Chiropractic in the United States:
Training, Practice, and Research
Daniel C. Cherkin, PhD
Senior Scientific Investigator
Center for Health Studies
Group Health Cooperative of Puget Sound
Robert D. Mootz, DC
Associate Medical Director for Chiropractic
Department of Labor and Industries
This project was supported by grant number HS07915 from the Agency for Health Care Policy and Research
AHCPR Publication No. 98-N002
Alan H. Adams, DC
Daniel C. Cherkin, PhD
Ian D. Coulter, PhD
Cheryl Hawk, DC, PhD
Gail A. Jensen, PhD
William C. Meeker, DC, MPH
Robert D. Mootz, DC
Reed B. Phillips, DC, PhD
Ruth Sandefur, DC, PhD
Paul G. Shekelle, MD, PhD
Howard T. Vernon, DC
TABLE OF CONTENTS
I. A Brief History of Chiropractic
II. Chiropractic Belief Systems
III. Chiropractic Training
IV. Supply, Distribution, and Utilization of Chiropractors in
the United States
V. Licensure and Legal Scope of Practice
VI. Insurance Coverage of Chiropractic Services
VII. Chiropractic in the Health Care System
VIII. Content of Practice
IX. Chiropractic Research
X. Biological Rationale for Possible Benefits of Spinal
XI. Benefits and Risks of Spinal Manipulation
XII. Synopsis, Research Priorities, and Policy Issues
One hundred years ago, the founder of the chiropractic profession, D. D. Palmer, reportedly used spinal manipulation to restore a deaf janitors hearing. A series of events following this dramatic incident ultimately led to the establishment of what is now one of the largest health care professions in the United States. From its beginnings, this new profession eschewed more invasive treatments in favor of spinal adjusting (or manipulation) as its central approach to care. During much of its first century of existence, chiropractic was shunned by the medical profession and remained on the fringe of mainstream health care. In fact, as recently as 1980, the American Medical Associations Principles of Medical Ethics proscribed any associations between physicians and chiropractors or other "unscientific practitioners."
In the past 10 to 15 years there have been dramatic changes both within the chiropractic profession and in the relationship between chiropractic and the health care system. Within the profession, significant progress has been made to upgrade the quality of training at the 17 accredited chiropractic colleges in North America. In addition, a small cadre of chiropractic researchers has been trained, initially with grant support from various chiropractic foundations and more recently from the Federal government. As a result, chiropractic researchers have become involved in a variety of studies, including randomized clinical trials, evaluating the effectiveness of spinal manipulation.
Outside of the profession, studies began to document the major role that chiropractors were playing in the care of persons with back and neck problems in spite of the absence of an experimentally validated biological mechanism for the effectiveness of manipulation (Von Kuster, 1980; Mugge, 1986; Shekelle, 1991). Other studies documented high levels of patient satisfaction among persons seeking chiropractic care (Cherkin, 1989; Kane, 1974; Carey, 1995). Persons with back pain who received care from chiropractors were found to be much more satisfied with all aspects of their care than patients of medical doctors (Cherkin, 1989). Several nonrandomized studies have also suggested that chiropractic treatment may be more effective than medical treatment for back pain among injured workers (Assendelft, 1993).
It soon became clear that, even though the effectiveness of chiropractic care remained to be evaluated in a scientifically rigorous manner, chiropractors appeared to be meeting the needs of many Americans suffering from back and neck pain. Whether their apparent success was due to the self-selection of patients with strongly favorable beliefs and expectations about chiropractic, to nonspecific effects of chiropractic treatment, to the confident, positive, and caring attitude common to many chiropractors, or to efficacy of spinal manipulation or other specific chiropractic treatments was not known. Nevertheless, because most standard medical treatments for back pain were of questionable value (Deyo, 1983), chiropractic appeared to many to be a reasonable alternative.
In the past 5 years, spinal manipulation has been the focus of evidence-based literature syntheses and meta-analyses performed by both medical and chiropractic researchers (Anderson, 1992; Shekelle, 1992; Koes, 1991). A formal meta-analysis of the literature concluded that spinal manipulation was of short-term benefit for patients with uncomplicated acute low back pain but that there was insufficient evidence for or against manipulation for patients with nerve root pain or chronic back pain (Shekelle, 1992). A blinded systematic literature review of 35 randomized clinical trials concluded that although the results were promising, the efficacy of manipulation had not yet been convincingly demonstrated (Koes, 1991). Although only five of the randomized trials involved manipulation by a chiropractor, the findings of these literature syntheses provided objective evidence that spinal manipulation was probably at least as effective for low back pain as most standard medical treatments.
Evidence-based national guidelines for the diagnosis and treatment of low back pain have recently been published in the United States (Bigos, 1994) and Great Britain (CSAG, 1994). Guided by the same scientific evidence for manipulation used in the literature syntheses, both national guidelines concluded that manipulation can be helpful for patients with acute low back pain without radiculopathy. Because more than 90 percent of spinal manipulations in the United States are performed by chiropractors (Shekelle, 1992), these recommendations were seen by many to be tantamount to the endorsement of chiropractic manipulation. Thus, almost exactly 100 years after D. D. Palmers legendary success using spinal manipulation, this technique and the profession most closely associated with its use, chiropractic, have gained a legitimacy within the United States health care system that until very recently seemed unimaginable.
Because of the rapidity of the changes in how spinal manipulation and chiropractic are viewed and the fact that many practicing physicians entered practice during an era when organized medicine portrayed chiropractors as "quacks," the majority of medical doctors have had little interaction with chiropractors and know very little about them. In view of the growing popularity and legitimacy of chiropractic care, it is important that health care providers, insurers, policymakers, and persons with back pain have a clear understanding of the current capabilities and limitations of chiropractic care. At present, sources of information about chiropractors and their care are widely scattered, often biased, and, due to the rapid changes affecting the profession, often out of date.
This monograph, which reflects a collaboration among scholars, researchers, and practitioners from both the medical and chiropractic communities, attempts to provide an unbiased overview of what is and is not known about the profession and practice of chiropractic. Contributors were selected based on their recognized national expertise in one or more of the topics covered in the monograph. All of the individuals involved with this project shared the vision of producing a monograph that presented a comprehensive and balanced overview of the chiropractic profession and its current and future potential role in the United States health care system. It is hoped that this information will not only help policymakers identify the most appropriate role for chiropractors in the health care system of the future, but will also help health care providers and back pain sufferers better understand both the value and limitations of chiropractic.
We are profoundly grateful to the authors whose contributions made this monograph possible, to Dakota Duncan for her extensive help with manuscript preparation, and to Janet Street, MN, CPNP, for project management. In addition we wish to thank Larry Rister, Louis Sportelli, DC, Gary Schultz, DC, Daniel Hansen, DC, Christine Goertz, DC, and Joseph Keating, PhD, for assistance in gathering information and providing access to otherwise unavailable data. We are also grateful to the Agency for Health Care Policy and Research, which provided the financial support necessary for this project. Finally, we would like to thank Peter Curtis, MD, Richard Deyo, MD, MPH, Daniel Hansen, DC, Ted Kaptchuk, OMD, Gary Schultz, DC, John Triano, MA, DC, and James Weinstein, DO, MPH, who served as independent reviewers for this monograph. Their contributions substantially improved the clarity and accuracy of the final product.
Daniel C. Cherkin, PhD
Robert D. Mootz, DC
Anderson R, Meeker W, Wirick B, Mootz R, Kirk D. A meta-analysis of clinical trials of manipulation. J Manipulative Physiol Ther 1992:15(3):181-94.
Assendelft WJJ, Bouter LM. Does the goose really lay golden eggs? A methodological review of workmens compensation studies. J Manipulative Physiol Ther 1993;16:161-8.
Bigos S, Bowyer O, Braen G, et al. Acute Low Back Problems in Adults. Clinical Practice Guideline No. 14. AHCPR Publication No. 95-0642. Rockville, MD: Agency for Health Care Policy and Research, Public Health Service, US Department of Health and Human Services, December 1994.
Carey TS, Garrett J, Jackman A, McLaughlin C, et al. The outcomes and costs of care for acute low back pain among patients seen by primary care practitioners, chiropractors, and orthopedic surgeons. N Engl J Med 1995;333:913-7.
Cherkin DC, MacCornack FA. Patient evaluations of low back pain care from family physicians and chiropractors. West J Med 1989;150:351-5.
Clinical Standards Advisory Group (Professor Michael Rosen, Chair). Report of a CSAG Committee on Back Pain, London, HMSO, May, 1994.
Deyo RA. Conservative therapy for low back pain. JAMA 1983;250:1057-62.
Kane RL, Olsen D, Leymaster C, Woolley FR, Fisher FD. Manipulating the patient: a comparison of the effectiveness of physician and chiropractor care. Lancet 1974;1:1333-6.
Koes BW, Assendelft WJJ, van der Heijden GJMG, Bouter LM, Knipschild PG. Spinal manipulation and mobilization for back and neck pain: a blinded review. BMJ 1991;303:1298-1303.
Mugge RH. Utilization of Chiropractic Services in the United States. National Center for Health Statistics. Paper prepared for presentation at the Meetings of the American Public Health Association in Las Vegas, NV, Oct. 1, 1986.
Shekelle PG, Brook RH. A community-based study of the use of chiropractic services. Am J Publ Hlth 1991;81:439-42.
Shekelle PG, Adams AH, Chassin MR, Hurwitz EL, Brook RH. Spinal manipulation for low-back pain. Ann Intern Med 1992;117(7):590-8.
Von Kuster T, Jr. Chiropractic Health Care: A National Study of Cost of Education, Service, Utilization, Number of Practicing Doctors of Chiropractic and Other Key Policy Issues. Washington, DC: The Foundation for the Advancement of Chiropractic Tenets and Science, 1980.
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