The ScienceBasedMedicine.org Reference Pages are reviews of topics relevant to science and medicine. Each consists of a concise overview of the topic from a scientific perspective, an index of the most relevant posts here on SBM, links to some external resources we recommend, and our summaries of the most interesting and important research. These pages are a work in progress, and we are actively developing them over the summer and fall of 2013, starting with acupuncture, chiropractic, homeopathy, and vaccines & autism.
Overview of Chiropractic
Chiropractic was invented by D. D. Palmer, Sep 18, 1895 when he adjusted the spine of a deaf man and allegedly restored his hearing (a claim that is highly implausible based on what we know of anatomy). Based on this one case, Palmer decided that all disease was due to subluxation: 95% to subluxations of the spine and 5% to subluxations of other bones.
The rationale for chiropractic hinges on three postulates:
- Bones are out of place
- Bony displacements cause nerve interference
- Manipulating the spine replaces the bones, removing the nerve interference and allowing Innate (a vitalistic life force) to restore health.
There is no credible evidence to support any of these claims.
Real subluxations (partial dislocations) show up on x-ray. Chiropractic “subluxations” don’t. In view of the negative x-ray evidence, chiropractic was forced to change its definition of a subluxation from “a bone out of place” to “a complex of functional and/or structural and/or pathological articular changes that compromise neural integrity and may influence organ system and general health.”
Chiropractors are divided into straights and mixers. The straights limit themselves to chiropractic adjustments; the mixers add a variety of other methods ranging from massage to outright quackery like applied kinesiology. Upper cervical chiropractors focus on the atlas, the top cervical vertebra.
In over a century, chiropractic research has produced no evidence to support the postulates of chiropractic theory and little evidence that chiropractic treatments provide objective benefits. Research on spinal manipulation is inherently difficult, because double blind studies are impossible and even single blind studies are problematic; a placebo response is hard to rule out.
There is good evidence that spinal manipulation therapy (SMT) is effective for some patients with low back pain but that it is not superior to other treatments. There is controversial evidence of lesser quality supporting the use of manipulation for neck pain and headaches. SMT is not exclusive to chiropractic: it is also used by physical therapists, doctors of osteopathy, and others. There is no acceptable evidence that chiropractic can improve the many other health problems it claims to benefit, from colic to asthma. There is no evidence to support the practice of adjusting the spines of newborns in the delivery room or providing repeated lifelong adjustments to maintain health or prevent disease.
Up to half of patients report short-term adverse effects from manipulation, such as increased local or radiating pain; and there is a rare but devastating complication of neck manipulation: it can injure the vertebrobasilar arteries and cause stroke, paralysis, and death. Some chiropractors do not accept the germ theory of disease and only about half of them support immunization. Many of them discourage proven treatments with drugs and surgery and many want to take on the role of primary health care provider.
In their book Trick or Treatment, Simon Singh and Edzard Ernst reviewed the evidence for chiropractic and concluded: “Chiropractors… might compete with physiotherapists in terms of treating some back problems, but all their other claims are beyond belief and can carry a range of significant risks.”
Index of SBM Posts about Chiropractic
Outside Resources about Chiropractic
- Chirobase.org (Stephen Barrett)
- Homola, Samuel. Inside Chiropractic: A Patient’s Guide (Consumer Health Library), Prometheus, 1999.
- EBM-First. Chiropractic> Research and efficacy.
- Benedetti, Paul and Wayne Macphail. (2003). Spin Doctors: The Chiropractic Industry Under Examination. Dundurn Press, 2003.
- Magner, George. Chiropractic: The Victim’s Perspective. Amherst, N.Y., Prometheus Books, 1995.
- NCAHF Position Paper on Chiropractic
- NCAHF Fact Sheet on Chiropractic
Summary of Key Research about Chiropractic
Subluxation theory: chiropractic’s defining idea
Mirtz TA, Morgan L, Wyatt LH, Greene L. An epidemiological examination of the subluxation construct using Hill’s criteria of causation. Chiropractic & Osteopathy 2009, 17:13, 2009.
This landmark paper penned by four chiropractors is a strong indictment of a philosophical pillar of their own profession, subluxation theory. Although a bit of a moving target over the years, subluxation theory generally refers to idea that spinal joint dysfunctions have broad health significance, which has been a major component of chiropractic thought since the founding of the profession (see Homola, Subluxation Theory: A Belief System That Continues to Define the Practice of Chiropractic). Dr. Harriet Hall in The End of Chiropractic, one of the most commented-on posts from that year:
Timothy A. Mirtz, Lon Morgan, Lawrence H. Wyatt, and Leon Greene analyze the peer-reviewed chiropractic literature in the light of Hill’s criteria, the most commonly used model for evaluating whether a suspected cause is a real cause. They ask whether the evidence shows that chiropractic subluxations cause interference with the nervous system and whether they cause disease. The evidence fails to fulfill even a single one of Hill’s nine criteria of causation.
Mirtz et al. conclude (emphasis added):
There is a significant lack of evidence in the literature to fulfill Hill’s criteria of causation as regards chiropractic subluxation. No supportive evidence is found for the chiropractic subluxation being associated with any disease process or of creating suboptimal health conditions requiring intervention. Regardless of popular appeal this leaves the subluxation construct in the realm of unsupported speculation. This lack of supportive evidence suggests the subluxation construct has no valid clinical applicability.
Cassidy JD, Boyle E, Côté P, He Y, Hogg-Johnson S, Silver FL, Bondy SJ. Risk of Vertebrobasilar Stroke and Chiropractic Care: Results of a Population-Based Case-Control and Case-Crossover Study. Spine (Phila Pa 1976). 2008 Feb 15;33(4 Suppl):S176-83.
Since its publication, “the Cassidy paper” has been the defensive citation used by chiropractors to respond to accusations that neck adjustments involve a risk of stroke, and therefore should not be conducted without proven benefit and informed consent. The abstract seems to strongly exonerate chiropractors: “We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.”
“But abstracts are like movie trailers,” as Dr. Mark Crislip wrote. “They give a flavor of the movie, but often leave out many important plot devices and characters. … If you were to read this article in its entirety, you would not be so sanguine about the safety of chiropractic.” He goes on to explain exactly why in one of SBM’s earliest popular posts, Chiropractic and Stroke: Evaluation of One Paper.
Spinal manipulative therapy (especially for back pain)
Rubinstein SM, Terwee CB, Assendelft WJJ, de Boer MR, van Tulder MW. Spinal manipulative therapy for acute low-back pain. Cochrane Database of Systematic Reviews 2012, Issue 9. Art. No.: CD008880.
If it were possible to report good news about spinal manipulation, it would be in this large Cochrane review of the science. Unfortunately, the good news is not here to report. Historically, spinal manipulative therapy (SMT, a.k.a. chiropractic adjustment) for acute low back pain has been regarded as the best example of evidence-based care routinely offered (primarily) by the chiropropractic profession. Even many fierce critics of chiropractic have supported this claim (or at least left it alone while focusing on other issues, e.g. the risks of cervical manipulation). Nevertheless, critics have pointed out that even this “best” use of SMT has been damned with faint praise by the research. This meta-analysis supports the most critical view: the authors concluded that “SMT is no more effective in participants with acute low-back pain” than shams and placebos. Despite this, the rest of their conclusions seem crafted to prolong the controversy. They explain to clinicians why they should still refer patients for SMT (“preferences” and “costs”); they say that more research is needed to “examine specific subgroups.” (This is based on the rather faint hope that SMT might work so well for an unknown subcategory of patients that they can pull up the average.) And they say there’s a need for “an economic evaluation,” but a treatment cannot be “cost effective” if it is not effective.
The conclusions of this review are also backed up by another major review, the “Bronfort report” on the effectiveness of mannual therapies:
Bronfort G, Haas M, Evans R, Leininger B, Triano J. Effectiveness of manual therapies: the UK evidence report. Chiropr Osteopat. 2010; 18: 3.
This review of all manual therapies focusses mainly on spinal manipulative therapy and massage therapy for low back and neck pain, with underwhelming results: both are “effective” in some circumstances but certainly not impressively so, and generally no different from other therapies that help a little but haven’t exactly put a dent in the epidemic. For instance, the authors write that SMT is effective but “similar in effect to other commonly used efficacious therapies such as usual care, exercise, or back school.” Unfortunately, “back school” is not exactly well known for curing low back pain.
Together, the Bronfort and Rubinstein reviews make it clear that spinal manipulative therapy is probably only of minor clinical value, at best.
Ernst E, Carter PH. A systematic review of systematic reviews of spinal manipulation. J R Soc Med 99:192,196, 2006.
Summary: A systematic review of systematic reviews published between 2000 and 2005, based on 16 studies that met the criteria. “Overall, the demonstrable benefit of SM seems to be minimalin the case of acute or chronic back pain; controversial inthe case of headache; or absent for all other indications… we have found no convincing evidence from systematicreviews to suggest that SM is a recommendable treatment optionfor any medical condition.”
Assendelft WJJ, Morton SC, Yu El, Suttorp MJ. Spinal manipulative therapy for low-back pain. Cochrane review 2004.
Summary: A systematic review of 39 trials found that spinal manipulation was more effective in reducing pain and improving the ability to perform everyday activities than sham therapy and therapies already known to be unhelpful. It was no more or less effective than medication for pain, physical therapy, exercises, back school, or the care given by a general practitioner.
Gross A, Hoving JL, Haines T, Goldsmith CH, Kay TM, Aker P, Bronfort G. Manipulation and mobilization for mechanical neck disorders. Cochrane Review, 2004.
Summary: A systematic review of 33 trials showed that multimodal care with mobilization and manipulation combined with exercise was superior to no treatment, that manipulation was not superior to mobilization, and that manipulation and mobilization alone were not superior to placebo, control groups and other treatments.
Gouveia LO, Castanho P, Ferreira JJ. Safety of chiropractic interventions: a systematic review. Spine 34(11) E405-13. 2009.
Summary: A systematic review of 46 studies found that 33-60% of patients receiving spinal manipulation treatment report short-term adverse effects such as increased pain, radiation of pain, headaches, vertigo and even loss of consciousness. It acknowledged that serious complications occur but was unable to reliably estimate their incidence. This study was discussed at Adverse Effects of Chiropractic
Rothwell, DM, Bondy SJ, Williams JI. Chiropractic manipulation and stroke: A Population-based case-control study. Stroke 32:1054, 2001.
Summary: Patients with a vertebrobasilar artery stroke who were under the age of 45 were 5 times as likely as controls to have visited a chiropractor during the week preceding their stroke.
Cherkin DC, Deyo RA, Battie M, Street J, Barlow W. A comparison of physical therapy, chiropractic manipulation, and provision of an educationsl booklet for the treatment of patients with low back pain. NEJM, 339:Vol 15:1021-1029, 1998.
Summary: “For patients with low back pain, the McKenzie methodof physical therapy and chiropractic manipulation had similareffects and costs, and patients receiving these treatments hadonly marginally better outcomes than those receiving the minimalintervention of an educational booklet. Whether the limitedbenefits of these treatments are worth the additional costsis open to question.”