No evidence that spinal manipulations work for non-musculoskeletal conditions

A substantial number of patients globally receive spinal manipulative therapy (SMT) to manage non-musculoskeletal disorders. However, the efficacy and effectiveness of these interventions to prevent or treat non-musculoskeletal disorders remain controversial.

A Global Summit of international chiropractors and scientists conducted a systematic review of the literature to determine the efficacy and effectiveness of SMT for the primary, secondary and tertiary prevention of non-musculoskeletal disorders. The Global Summit took place on September 14-15, 2019 in Toronto, Canada. It was attended by 50 chiropractic researchers from 8 countries and 28 observers from 18 chiropractic organizations. Participants met the following criteria: 1) chiropractor with a PhD, or a researcher with a PhD (not a chiropractor) with research expertise in chiropractic; 2) actively involved in research (defined as having published at least 5 peer-reviewed papers over the past 5 years); and 3) appointed at an academic or educational institution. In addition, a small group of researchers who did not meet these criteria were invited. These included three chiropractors with a strong publication and scientific editorial record who did not have a PhD (SMP, JW, and HS) and two early career researchers with expertise within the area of chiropractic and pseudoscience (ALM, GG). Participants were invited by the Steering Committee using purposive and snowball sampling methods. At the summit, participants critically appraised the literature and synthesized the evidence.

They searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, the Cumulative Index to Nursing and Allied Health, and the Index to Chiropractic Literature from inception to May 15, 2019, using subject headings specific to each database and free text words relevant to manipulation/manual therapy, effectiveness, prevention, treatment, and non-musculoskeletal disorders. Eligible for review were randomized controlled trials published in English. The methodological quality of eligible studies was assessed independently by reviewers using the Scottish Intercollegiate Guidelines Network (SIGN) criteria for randomized controlled trials. The researchers synthesized the evidence from articles with high or acceptable methodological quality according to the Synthesis without Meta-Analysis (SWiM) Guideline. The final risk of bias and evidence tables were reviewed by researchers who attended the Global Summit and 75% (38/50) had to approve the content to reach consensus.

A total of 4997 citations were retrieved, and 1123 duplicates were removed, and 3874 citations were screened. Of those, the eligibility of 32 articles was evaluated at the Global Summit and 16 articles were included in the systematic review. The synthesis included 6 randomized controlled trials with acceptable or high methodological quality (reported in 7 articles). These trials investigated the efficacy or effectiveness of SMT for the management of

• infantile colic,
• childhood asthma,
• hypertension,
• primary dysmenorrhea,
• migraine.

None of the trials evaluated the effectiveness of SMT in preventing the occurrence of non-musculoskeletal disorders. A consensus was reached on the content of all risk of bias and evidence tables. All randomized controlled trials with high or acceptable quality found that SMT was not superior to sham interventions for the treatment of these non-musculoskeletal disorders.

Six of 50 participants (12%) in the Global Summit did not approve the final report.

The authors concluded that our systematic review included six randomized clinical trials (534 participants) of acceptable or high quality investigating the efficacy or effectiveness of SMT for the treatment of non-musculoskeletal disorders. We found no evidence of an effect of SMT for the management of non-musculoskeletal disorders including infantile colic, childhood asthma, hypertension, primary dysmenorrhea, and migraine. This finding challenges the validity of the theory that treating spinal dysfunctions with SMT has a physiological effect on organs and their function. Governments, payers, regulators, educators, and clinicians should consider this evidence when developing policies about the use and reimbursement of SMT for non-musculoskeletal disorders.

I would have formulated the conclusions much more succinctly:

As has already been shown repeatedly, there is no sound evidence that SMT is effective for non-musculoskeletal conditions.