MD, PhD, FMedSci, FRSB, FRCP, FRCPEd

Systematic reviews are aimed at summarising and critically evaluating the evidence on a specific research question. They are the highest level of evidence and are more reliable than anything else we have. Therefore, they represent a most useful tool for both clinicians and researchers.

But there are, of course, exceptions. Take, for instance, this recent systematic review by researchers from the

  • Texas Chiropractic College, Pasadena, the Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport,
  • Department of Planning, Policy and Design, University of California, Irvine,
  • VA Puget Sound Health Care System, Tacoma,
  • New York Chiropractic College, Seneca Falls,
  • Logan University College of Chiropractic, Chesterfield,
  • University of Western States, Portland.

Its purpose was to evaluate the effectiveness of conservative non-drug, non-surgical interventions, either alone or in combination, for conditions of the shoulder. The review was conducted from March 2016 to November 2016 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and was registered with PROSPERO. Eligibility criteria included randomized controlled trials (RCTs), systematic reviews, or meta-analyses studying adult patients with a shoulder diagnosis. Interventions qualified if they did not involve prescription medication or surgical procedures, although these could be used in the comparison group or groups. At least 2 independent reviewers assessed the quality of each study using the Scottish Intercollegiate Guidelines Network checklists. Shoulder conditions addressed were

  • shoulder impingement syndrome (SIS),
  • rotator cuff-associated disorders (RCs),
  • adhesive capsulitis (AC),
  • nonspecific shoulder pain.

Twenty-five systematic reviews and 44 RCTs met inclusion criteria. Low- to moderate-quality evidence supported the use of manual therapies for all 4 shoulder conditions. Exercise, particularly combined with physical therapy protocols, was beneficial for SIS and AC. For SIS, moderate evidence supported several passive modalities. For RC, physical therapy protocols were found beneficial but not superior to surgery in the long term. Moderate evidence supported extracorporeal shockwave therapy for calcific tendinitis RC. Low-level laser was the only modality for which there was moderate evidence supporting its use for all 4 conditions.

The authors concluded that the findings of this literature review may help inform practitioners who use conservative methods (eg, doctors of chiropractic, physical therapists, and other manual therapists) regarding the levels of evidence for modalities used for common shoulder conditions.

This review has so many defects that it would be boring to list them here.

The PRISMA guidelines  – I happen to be a co-author – state, for instance, that the abstract (the above text is from the abstract) should provide a structured summary including, as applicable: background; objectives; data sources; study eligibility criteria, participants, and interventions; study appraisal and synthesis methods; results; limitations; conclusions and implications of key findings; systematic review registration number. It is obvious that the review authors have omitted several of these items.

And that is just the abstract!  There is much, much more to criticise in this paper.

The most striking deficit, in my view, is the useless conclusion: the one from the abstract (the part of the paper that will be read most widely) could have been written before the review had even been started. It is therefore not based on the data presented. Crucially it does not match the stated aim of this review (“to evaluate the effectiveness of conservative…interventions”).

But why? Why did the authors bother to follow PRISMA? Why did they formulate this bizarre conclusion in their abstract? Why did they do a review in the first place?

I fear, the answers might be embarrassingly simple:

  • They only pretended to follow PRISMA guidelines because that gives their review a veneer of respectability.
  • They formulated the conclusions because otherwise they would have needed to state that the evidence for manual therapy is less than convincing.
  • They conducted the review to promote chiropractic, and when the data were not as they had hoped for, they just back-paddled in an attempt to hide the truth as much as possible.

If this were an isolated case, I would not have bothered to mention it. But sadly, in the realm of chiropractic (and alternative medicine in general) we currently witness a plethora of rubbish reviews (published by rubbish journals). To the naïve observer, they might look rigorous and therefore they will be taken seriously. The end-effect of this pollution of the literature with rubbish is that we get a false-positive impression about the validity of the treatments in question. Consequently, we will see a host of wrong decisions on all levels of healthcare.

The big question is: HOW DO WE PROTECT OURSELVES FROM THIS DANGEROUS TREND?

I only see one solution: completely disregard certain journals that have been identified to regularly publish nonsense. Sadly, the wider medical community is far from having arrived at this point. As far as I can see, the problem has not even been identified yet as a serious issue that needs addressing. For the foreseeable future, we will probably have to live with this type of pollution of our medical literature.

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