No evidence that spinal manipulation improves immune function

Absurd claims about spinal manipulative therapy (SMT) improving immune function have increased substantially during the COVID-19 pandemic. Is there any basis at all for such notions?

The objective of this systematic review was to identify, appraise, and synthesize the scientific literature on the efficacy and effectiveness of SMT in preventing the development of infectious disease or improving disease-specific outcomes in patients with infectious disease and to examine the association between SMT and selected immunological, endocrine, and other physiological biomarkers.

A literature search of MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, the Index to Chiropractic Literature, the Cochrane Central Register of Controlled Trials, and Embase was conducted. Randomized clinical trials and cohort studies were included. Eligible studies were critically appraised, and evidence with high and acceptable quality was synthesized using the Synthesis Without Meta-Analysis guideline.

A total of 2593 records were retrieved; after exclusions, 50 full-text articles were screened, and 16 articles reporting the findings of 13 studies comprising 795 participants were critically appraised. No clinical studies were located that investigated the efficacy or effectiveness of SMT in preventing the development of infectious disease or improving disease-specific outcomes among patients with infectious disease. Eight articles reporting the results of 6 high- and acceptable-quality RCTs comprising 529 participants investigated the effect of SMT on biomarkers. Spinal manipulative therapy was not associated with changes in lymphocyte levels or physiological markers among patients with low back pain or participants who were asymptomatic compared with sham manipulation, a lecture series, and venipuncture control groups. Spinal manipulative therapy was associated with short-term changes in selected immunological biomarkers among asymptomatic participants compared with sham manipulation, a lecture series, and venipuncture control groups.

The authors concluded that no clinical evidence was found to support or refute claims that SMT was efficacious or effective in changing immune system outcomes. Although there were limited preliminary data from basic scientific studies suggesting that SMT may be associated with short-term changes in immunological and endocrine biomarkers, the clinical relevance of these findings is unknown. Given the lack of evidence that SMT is associated with the prevention of infectious diseases or improvements in immune function, further studies should be completed before claims of efficacy or effectiveness are made.

I fully agree with the data as summarised in this paper. Yet, I find the conclusions a bit odd. The authors of this paper are chiropractors who declare the following conflicts of interest: Dr Côté reported receiving grants from the College of Chiropractors of British Columbia during the conduct of the study and grants from the Canadian Chiropractic Research Foundation, travel expenses from the World Federation of Chiropractic, and personal fees from the Canadian Chiropractic Protective Association outside the submitted work. Dr Cancelliere reported receiving grants from the Canadian Chiropractic Research Foundation outside the submitted work. Dr Mior reported receiving grants from the College of Chiropractors of British Columbia during the conduct of the study and grants from the Canadian Chiropractic Association and the Ontario Chiropractic Association outside the submitted work. Dr Hogg-Johnson reported receiving grants from the College of Chiropractors of British Columbia during the conduct of the study and grants from the Canadian Chiropractic Research Foundation outside the submitted work. No other disclosures were reported. The research was supported by funding from the College of Chiropractors of British Columbia to Ontario Tech University, the Canada Research Chairs program (Dr Côté), and the Canadian Chiropractic Research Foundation (Dr Cancelliere).

Would authors independent of chiropractic influence have drawn the same conclusions? I doubt it! While I do appreciate that chiropractors published these negative findings prominently, I feel the conclusions could easily be put much clearer:

There is no clinical evidence to support claims that SMT is efficacious or effective in changing immune system outcomes. Further studies in this area are not warranted.