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Chiropractic Research Retrospective

By George McClelland, DC

Reprinted with permission from the Journal of the American Chiropractic Association, March 2000.

THIRTY YEARS AGO, when I finished chiropractic college, chiropractic research was an oxymoron. In fact, research specific to spinal manipulative therapy, or more specifically chiropractic manipulative therapy/adjustment as performed by doctors of chiropractic, just didn’t exist. Since that time, this has changed dramatically—especially over the last 20 years. In fact, it was only 20 years ago this year that the first peer-reviewed, and subsequently indexed, scientific journal was developed in the chiropractic profession, now known as the Journal of Manipulative and Physiological Therapeutics (JMPT). Even 13 years ago, there was only this one scientific journal in the chiropractic profession. Today, there are more than 10 peer-reviewed scientific chiropractic journals in North America alone.

One of the primary reasons for this burst of chiropractic-related research in the last 20 years is an organization called the Foundation for Chiropractic Education and Research (FCER). This organization was founded in 1944 as a subsidiary organization of the American Chiropractic Association’s predecessor, the National Chiropractic Association. It was not, however, until 1981 that FCER began making major strides toward developing, funding, and administering chiropractic research with a strong focus on clinical studies. In fact, an October 1998 article written by Keating, et al., in JMPT noted that FCER had funded the largest number of papers (24%) published in JMPT between 1989 and 1996. The paper also noted that this was a seven-fold increase in the number of controlled clinical trials performed in the previous 10 years. Through the primary support of the American Chiropractic Association, the National Chiropractic Mutual Insurance Company, and the chiropractic profession at large, FCER (since 1980) has awarded 160 grants, which have resulted in 233 publications and 251 presentations. Additionally, it has funded 90 post-doctoral fellowships, as well as 17 research residencies in chiropractic colleges. This has resulted in just under $10 million awarded within the chiropractic profession. The FCER has been, and continues to be, the largest, most active, and well-known research development and funding agency in the chiropractic profession.

So, what is the quality of the research being turned out in chiropractic today? A recent critical literature review of 27 randomized clinical trials published between 1966 and 1995 addressing neck pain was published in the Scandinavian Journal of Rehabilitative Medicine (Kjellman et al, 1999; Vol. 31, pp. 139-152). This meta-analysis by Kjellman ranked an FCER-funded study by Patrick Boline, et al., at Northwestern Chiropractic College the highest for methodological quality of all the studies reviewed. The Boline study, entitled, "Spinal Manipulation versus Amitriptyline for the Treatment of Chronic Tension-Type Headaches: A Randomized Clinical Trial," was published in JMPT in March/April 1995. That particular study shows very favorable longer-lasting results for tension headache sufferers that utilize manipulation versus amitriptyline. This is the second time the Boline study was ranked highest in a meta-analysis for methodological quality. The previous meta-analysis done by Hurwitz, et al., was published in Spine in 1996.

Probably the biggest splash that chiropractic or spinal manipulative therapy has made on the media front came in December 1994 with the federal government’s release of the Agency on Health Care Policy and Research’s (AHCPR) Clinical Practice Guideline #14, entitled, " Acute Lower Back Problems in Adults" Regarding spinal manipulation, the literature reviewed in that particular study included at least 29 controlled trials, nine of which focused on acute low-back problems. From that study, it was determined that spinal manipulation had the same level of efficacy as did non-steroidal anti-inflammatory drugs (NSAIDs). They also threw in certain over-the-counter analgesics, like Tylenol. Interestingly, there were only four randomized controlled trials (RCTs) for the NSAIDs. There were no other health care interventions (e.g., medications, physical therapy, surgery, or acupuncture) that came close to these in their established scientific evidence or acceptance by the panel of experts that reviewed them. Ever since the release of Guideline #14, chiropractic has been more accepted in the medical realm as being an effective treatment for acute low-back pain.

One other issue that came out of Guideline #14, as well as the British Guidelines for Low-Back Pain, which came out at about the same time, was the statement that most back problems clear up within 30 days. In fact, this point has been utilized by many third-party payers to limit intervention (especially chiropractic) in the treatment of low-back pain. A number of articles, however, have been published recently that take exception to this issue. Actually, these were highlighted best in an article in the Back Letter (1999, Vol. 14, No. 6, Lippincott, Williams & Wilkins), which made some strong points to the contrary. This article, entitled, "Acute Back Pain, Benign but Frequently Persistent," evaluated six different articles published in the scientific literature since 1986.

The key points of this article were:

  • Pain symptoms are likely to improve, but not disappear

  • Functional limitations are likely to lessen over time

  • Functional limitations may persist in a minority of patients

  • Predictors of chronicity are largely psychosocial

  • Viewing the course of back pain as acute or chronic may be an oversimplification

Probably the most noteworthy article in this group of six published studies was one entitled, "Outcome of Low-Back Pain in General Practice: A Perspective Study" (British Medical Journal, 1998; Vol. 316; pp. 1356-1359). This article by Peter Croft, et al., took to task the claim that 90 percent of episodes of low-back pain resolved within one month. In fact, in follow-up interviews with the patients in a family practice setting, they found that of 490 adults who presented with acute low-back pain, only 21 percent had completely recovered in a three-month period of time and, by the end of one year, only 25 percent had complete recovery. I especially like Croft’s characterization of low-back pain in which he stated, ‘It should be viewed as a chronic problem with an untidy pattern of grumbling symptoms and periods of relative freedom from pain and disability . . ."

A more recent study, entitled, "Chronic Spinal Pain Syndromes: A Clinical Pilot Trial Comparing Acupuncture, a Non-Steroidal Anti-Inflammatory Drug, and Spinal Manipulation" (JMPT, July/August 1999, Vol. 22, No. 6), evaluated 77 patients that were randomized into the three groups and found spinal manipulation superior to the other interventions. Dr. Lynton Giles and the other authors from the Townsville Spinal Pain Unit in Townsville, Australia, were pleased to find that one of their interventions provided significant positive outcomes: 30 percent for low-back pain on the Oswestry scale, 25 percent on the Neck Disability Index, and 50 percent on the Visual Analog Scale for low back—with 46 percent for upper back pain and 33 percent for neck pain. They were also quick to point out that guidelines need to be established for chronic spinal pain syndromes. Currently, similar studies are being pursued in the chiropractic profession.

One of the difficult aspects of developing appropriate clinical trials in the chiropractic profession is the determination of an appropriate placebo or sham to be utilized in a RCT. In fact, two recent studies funded and administered by FCER received considerable criticism regarding how benign the sham procedures (soft-tissue manipulation/massage) really may have been and what consequence the use of these shams may have afforded the study. The first of these studies, "A Comparison of Active and Simulated Chiropractic Manipulation as Adjunctive Treatment for Childhood Asthma" (New England Journal of Medicine, 1998, Vol. 339, No. 15, pp. 1013-1020), was written by Jeff Balon, et al., and found that chiropractic manipulative therapy gave no significant benefit over the other medical interventions in the treatment of childhood asthma. A second article, entitled, "Spinal Manipulative Therapy vs. a Low-Force Mimic Maneuver for Women with Primary Dysmenorrhea: A Randomized, Observer-Blinded, Clinical Trial" (Pain 1999), was performed by Maria Hondras, et al., and also did not support the greater effectiveness of spinal manipulation in the treatment of primary dysmenorrhea.

Because spinal manipulation requires physical contact with a patient, it has become very difficult to determine sham procedures that could be utilized in place of spinal manipulation to perform appropriate RCTs. In fact, a recent study by Donald Dishman, a researcher at New York Chiropractic College, demonstrated that the cutaneous nerve receptors could not determine between a soft-tissue sham procedure and a side-posture manipulation. This would seem to support that sham manipulative procedures, which include soft-tissue manipulation, would not be an appropriate contrast for spinal manipulative procedures. It is anticipated that Dr. Dishman’s article will be published in a scientific journal in the near future.

Another issue of great concern in the chiropractic profession is that of cervicogenic headaches. This refers to headaches that primarily have their origin in the neck. Although chiropractic has been managing this type of headache for the greater part of this century, it has only been in the last five years that there has been more research acknowledging the presence of cervicogenic headache and its management. Probably the most outspoken authority on this is a Dr. Peter Rothbart, a neurologist in Toronto, Canada, who was the subject of an article in the December 1995 Toronto Star. Dr. Rothbart noted that more than 80 percent of the headaches seen in his neurological clinic have their origins in the cervical spine.

A subsequent article in The Chiropractic Report, edited by David Chapman-Smith, also of Toronto, cited five different studies performed in the United States, Italy, Canada, and England in 1994 and 1995 that addressed this same type of headache. Three of these studies even addressed the effectiveness of spinal manipulation and the treatment of this headache form.

I had the opportunity in 1995, on behalf of ACA and FCER, to testify before the AHCPR’s panel on Chronic Pain Headache. Unfortunately, due to apparent funding changes for the AHCPR, that study and the consensus panel, which was being managed by Duke University, was dismantled. There was a resultant paper published last year that addressed migraine headache from the information gathered. The rest of the information that pertained to the more prevalent tension headache, as well as cervicogenic headache, was not published. Fortunately, through continued pressure by FCER, we have now worked out an arrangement with Duke University to develop a new study that would first of all look at the previously existing information on all forms of headache, including migraine, and add the current research since 1995. It is known that there is a much greater volume of information that pertains to favorable chiropractic management of multiple forms of headache. It is anticipated this new study could be submitted for publication within the next year.

Currently, there are at least two other asthma studies going on that look at the efficacy of chiropractic management and the use of spinal manipulation in the treatment and management of this chronic debilitating condition. One study is being done by Ray Hayek at Macquarie University in Australia. The preliminary results of this study were reported last year in Vancouver at the International Conference on Spinal Manipulation (ICSM) and appear to be more in line with the more positive case studies that have been experienced in chiropractic over the decades. Another asthma study is a pilot being done by Gert Bronfort at Palmer University in Davenport, Iowa. The paper from this study has already been submitted for publication.

Another study that was funded over five years ago by monies provided by NCMIC through FCER administration is the ABT Primary Care Study. The ABT Study has produced a number of papers for publication already. Two of these address wellness or maintenance care, as provided by chiropractors. These papers have been accepted for publication and are currently going through review. One outcome described in these papers was that elderly chiropractic patients under maintenance care had over a 70 percent reduction of average per capita expenditure for health care services, as compared to the national average.

Currently, there is a study going on at Harvard entitled, "Managed Care Alternative Medicine Pilot." This pilot study was assisted by funding from the chiropractic profession (FCER and NCMIC). As a result of the pilot’s success, a full-scale study has currently been funded by the National Center for Complementary and Alternative Medicine. This study will evaluate patients with back pain that will be randomized under managed care control to medical interventions or their choice of several complementary and alternative medicine procedures including chiropractic, acupuncture, and massage.

Certainly the Department of Defense’s (DOD) Chiropractic Demonstration Project, which has been in existence since 1995 and is currently being tested at 13 separate military sites, has great importance to ACA and the patients we serve. Although the DOD was authorized in 1993 (1993 Defense Authorization Bill) to commission doctors of chiropractic (DCs) in the military, it was not until the passage of the 1995 Defense Authorization Bill that funding was provided for this pilot program. It is our understanding that utilization, positive outcomes, and patient satisfaction have had high marks on this pilot study to date.

In addition to the above studies, there are several studies that are currently in publication or are at some level of completion. These include:

  • An evaluation of which forms of chiropractic manipulative therapy are better supported by the literature in the treatment of specific low-back pain complaints.

  • A comparative study of the treatment of sciatica utilizing chiropractic manipulative therapy, medication, and epidural steroids.

  • Dr. Gary Hack and his group of researchers are currently looking at the effectiveness of conservative management of the anatomical myodural connections that he discovered several years ago between the rectus capitus posterior minor and the dura mater, and its relationship to tension headaches.

  • There are a number of basic science studies that are going on using both the cat and rat models to determine what effects spinal mechanical misalignments, or subluxation if you will, have upon these animals.

I think we can at least say that chiropractic research is certainly no longer an oxymoron. It is apparent through the increase in collaborative research that has gone on in the scientific community, as well as the new federal funding sources that have opened up for chiropractic in the last five years, that although chiropractic research may be the "new kid on the block," it is definitely making itself known.

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