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Research Review By Dr. Ceara Higgins©


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Date Posted:

November 2018

Study Title:

Effect of chiropractic treatment on primary or early secondary prevention: a systematic review with a pedagogic approach


Goncalves G, Le Scanff C & Leboeuf-Yde C

Author's Affiliations:

CIAMS, University of Paris-Sud, University of Paris-Saclay, Orsay Cedex, France; CIAMS, University of Orleans, Orleans, France; Institut Franco Europeen de Chiropraxie, Ivry sur Seine, France.

Publication Information:

Chiropractic & Manual Therapies 2018; 26: 10 (full text available here)

Background Information:

Generally speaking, it is important to consider whether it is possible to prevent a disease from occurring, rather than wait to treat it once it is present. However, primary prevention (PP) or early secondary prevention is not always possible and can only be applied in conditions where the causes are known and avoidable or modifiable. It is also only practical to apply a preventive approach when it is less expensive and less likely to lead to adverse effects than the treatment itself.

Some medical conditions are known to be effectively prevented through PP or early secondary intervention. However, some chiropractors propose to prevent spinal problems and even disease in general through the treatment of spinal ‘subluxations’, even before the emergence of symptoms. This often includes disorders that are outside of the chiropractic scope of practice or even beyond the legal boundaries of chiropractic legislation (1).

The idea that spinal ‘subluxation’ can cause a host of diseases and that its correction can prevent these is not consistent with modern medical concepts that recognize the etiology of most diseases as multi-causal/factorial. Therefore, the idea that the correction of spinal ‘subluxation’ could overcome the combined effects of environmental, social, biological, and noxious lifestyle factors seems naïve and is without supporting evidence.

The ‘subluxation’ model is summarized as follows: 1) disturbances in the spine (‘subluxations’) exist; 2) these can cause a multitude of diseases; 3) ‘subluxations’ can be detected in a chiropractic examination before symptoms arise; 4) chiropractic adjustments can remove ‘subluxations’; 5) removing ‘subluxations’ results in improved health. To date there is no proof of the existence of the ‘subluxation’ and therefore, a causal link between spinal ‘subluxations’ and various diseases should not be implied. Finally, even if an improvement is seen in a condition following chiropractic treatment, it does not prove causation (especially when observed in one, or a very small number of people!). Without proof of a link between chiropractic treatment and primary prevention, it could be considered unethical for chiropractors to promote preventive treatments to their patients.

Therefore, this review asked the following questions:
  1. For which physical, non-musculoskeletal diseases has the effect/benefit of chiropractic treatment been studied in the chiropractic literature?
  2. Which study designs have been used?
  3. Were the designs appropriate to uncover effects of intervention?
  4. Was the basic methodological quality sufficient to make results credible?
  5. What evidence is there that chiropractic treatment can prevent disease or stop it in its early stage?

Pertinent Results:

Over 13 000 articles were originally scrutinized, but only 13 full text articles were included in the final review: 8 prospective clinical studies and 5 population studies published between 1997 and 2013. Five case reports were also assessed. Disorders or health states studied included lung function, systolic and diastolic blood pressure, visual acuity, obesity, infectious disease, mortality, diabetes mellitus, cholesterol levels, multiple conditions with dyslipidemia, cardiovascular disease risk factors, and four proxies for (or markers) of good health: salivary pH, plasma serum thiol, blood test immunological markers, and heart rate variability.

Most of the clinical studies were simple, descriptive, prospective designs without control groups. Only three included a control group; one with two identically treated groups with spinal manipulation added to one, one with a treatment and a placebo group, and one using a retrospective case-control study design. The retrospective case-control study was unlikely to have included similar patients making comparisons between groups non-credible.

Based on the included articles, no evidence of the effect of manipulative therapy/chiropractic treatment pertaining to primary or early secondary prevention of any disease could be found. Only one article, comparing real treatment (toggle recoil) to a sham treatment in patients with prehypertension or stage 1 hypertension, was of high enough quality to be used to draw conclusions on effect. This article showed an absence of effect of spinal manipulation (we’ve reviewed this paper on RRS Education previously). One other article was methodologically acceptable and looked at a possible added benefit with spinal manipulation in patients with primary dysfunctional breathing when combined with breathing retraining. Again, no benefit was found. All other articles were not found to be suitable for establishing an effect or benefit of chiropractic treatment.

Much of the existing literature in support of chiropractic treatment for PP or early secondary prevention is in the form of case studies. These are useful for identifying specific areas in need of further clinical studies, but should not be sufficient to make clinicians, nor patients, believe in a specific treatment effect.

Clinical Application & Conclusions:

This study found no evidence to support the notion that manipulative therapy/chiropractic care can prevent or stop early disease. Thus, the authors suggest that if the chiropractic profession wants to maintain credibility, political associations and educational institutions should not recommend spinal manipulation for the sole purpose of disease prevention unless appropriate, high quality research evidence can be produced to support this type of care.

Chiropractors can provide information and inspiration to help patients avoid preventable disorders and help them to monitor lifestyle factors and changing symptomatology suggestive of a disease condition. In the broader context of our role in a contemporary healthcare system, the high prevalence of back and neck problems in conjunction with their recurring nature underscores the need for chiropractors to care for people during acute episodes and guide them through the fluctuating nature of spinal pain conditions. This is where the bulk of our evidence lies, which makes one wonder why some chiropractors would feel the need to “extend their scope of practice to implausible areas, when there is so much to do in the musculoskeletal field”.

Study Methods:

Studies were found through a number of systematic searches performed in consultation with a librarian. Two authors independently selected articles. Searches were free text using terms related to chiropractic and prevention/wellness. The authors also scrutinized the reference lists of relevant articles, screened all issues of the Journal of Vertebral Subluxation Research, Journal of Chiropractic Medicine, Functional Neurology, and Rehabilitation and Ergonomics. No limitations were placed on publication year.

Abstracts and/or full texts were screened using the following criteria:

Inclusion Criteria:
  • Articles written in English
  • Published research articles that studied the clinical preventive effect of or benefit from manipulative therapy/chiropractic treatment in relation to PP and/or early secondary treatment of physical diseases/morbidity other than musculoskeletal disorders
  • Studies including early markers of ill health
  • Studies of prevention of early death
  • Clinical and epidemiological studies
  • Studies including chiropractic treatment, defined as any treatment provided by a chiropractor
  • Studies where outcomes were studied in a clinical context
Exclusion Criteria:
  • Reviews, discussion papers, abstract proceedings, comments, letters to the editor, and animal studies
  • Studies on risk of falling, improved sport performance, infertility, and pregnancy
  • Studies on wellness and general well-being measured exclusively through questionnaires
The authors designed five checklists to chart data in relation to the description of the reviewed articles and basic quality criteria, concentrating mainly on the study design. The checklists used are as follows:

Descriptive checklist for clinical studies:
  • First author, year of publication, name of journal, affiliation, country
  • Research questions(s)/purpose of the study
  • Type of manipulative therapy/chiropractic treatment
  • Outcome variables for studied condition
  • Authors’/author’s conclusion in relation to effect/benefit of chiropractic treatment
Quality checklist for clinical studies:
  • Methodological considerations
  • Design
  • Comparison with non-treated (placebo) or an otherwise treated group
  • Random and concealed allocation to treatment groups
  • Main outcome variable(s) validated in some way
  • Assessor blinded to treatment group
  • Were differences between groups tested for statistical significance in relation to effect/benefit of treatment
  • Comments by reviewers in relation to major methodological improvements needed to test effect/benefit of intervention
Descriptive checklist for population studies:
  • First author, year of publication, name of journal, affiliation, country
  • Research questions(s)/purpose of study
  • Design
  • Study population
  • Outcome variables
  • Which factors associated with cause were included?
  • Authors’/author’s conclusion in relation to effect/benefit of chiropractic treatment
Quality checklist for population studies:
  • Selection of study subjects
  • Response/Non-response comparison
  • Definition of chiropractic treatment
  • Outcome variables validated in some way
  • Control for other variables that could have an effect on outcomes
  • Comments by reviewers in relation to major methodological improvements needed to test effect/benefit of intervention
Descriptive checklist for case studies:
  • First author, year of publication, name of journal, affiliation, country
  • Disorder studied
  • Type of treatment
  • Author’/author’s conclusion in relation to effect/benefit of chiropractic treatment
Two authors independently extracted data with the option to consult the third author in cases of disagreement.

Study Strengths / Weaknesses:

  • The authors only utilized articles with a high level of methodological quality
  • The authors designed their own checklists to meet their specific needs. Thus, they are not validated for data collection. They did mention this in the paper and clarified that, due to the state of the literature they were investigating, a higher-level assessment (via a Cochrane method, for example) would not have been possible.
  • As with any review like this, it is possible that pertinent articles were missed.

Additional References:

  1. Schneider M, Murphy D, Hartvigsen J. Spine care as a framework for the chiropractic identity. J Chiropr Humanit 2016; 23(1): 14-21.

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