ChiroNexus recently listed the top 10 chiropractic studies of 2013. In my experience, chiropractic studies tend to be of poor quality. A media report says “study shows chiropractic works for X,” and when I look for the study it turns out to be a single case report or an uncontrolled study. When Simon Singh was sued by the British Chiropractic Association for saying chiropractic treatment for certain childhood ailments was bogus, the BCA responded with a list of 29 studies they said provided evidence for their claims. Steven Novella showed that out of 29 studies on the list, only 17 actually constituted evidence for 4 clinical claims, and those 17 were poor quality, cherry-picked, and too weak to support the claims. I have a copy of a chiropractic textbook entitled Somatovisceral Aspects of Chiropractic: An Evidence-Based Approach and there is nothing in it that would qualify as credible evidence to a science-based thinker. Chiropractic commenters on SBM have told us that modern chiropractic rejects the “subluxation” paradigm and relies on evidence, and I am always willing to look at new evidence and give chiropractors another chance to convince me that a reform movement is really underway, so I looked up the top 10 studies and read them. I was not impressed.
Note: This is a long article with mind-numbing details that will not be of interest to most readers. Feel free to scroll down to the Summary section. You can just read the bold-faced headings describing the claims of each study on the way down.
Also note: For those who want more detail, the “Study #” headings are links to the full text when available online, or to the PubMed citation.
Do not trust the cheering, for those persons would shout as much if you or I were going to be hanged.”
~ Oliver Cromwell
In the blogosphere, the proponents of chiropractic often quote the following paper, with the abstract:
Risk of Vertebrobasilar Stroke and Chiropractic Care
Results of a Population-Based Case-Control and Case-Crossover Study
Spine. 2008 Feb 15;33(4 Suppl):S176-83.
by Cassidy JD, Boyle E, Côté P, He Y, Hogg-Johnson S, Silver FL, Bondy SJ.
Why be different? Here is the abstract.
STUDY DESIGN: Population-based, case-control and case-crossover study. OBJECTIVE: To investigate associations between chiropractic visits and vertebrobasilar artery (VBA) stroke and to contrast this with primary care physician (PCP) visits and VBA stroke.
SUMMARY OF BACKGROUND DATA: Chiropractic care is popular for neck pain and headache, but may increase the risk for VBA dissection and stroke. Neck pain and headache are common symptoms of VBA dissection, which commonly precedes VBA stroke.
METHODS: Cases included eligible incident VBA strokes admitted to Ontario hospitals from April 1, 1993 to March 31, 2002. Four controls were age and gender matched to each case. Case and control exposures to chiropractors and PCPs were determined from health billing records in the year before the stroke date. In the case-crossover analysis, cases acted as their own controls.
RESULTS: There were 818 VBA strokes hospitalized in a population of more than 100 million person-years. In those aged <45 years, cases were about three times more likely to see a chiropractor or a PCP before their stroke than controls. Results were similar in the case control and case crossover analyses. There was no increased association between chiropractic visits and VBA stroke in those older than 45 years. Positive associations were found between PCP visits and VBA stroke in all age groups. Practitioner visits billed for headache and neck complaints were highly associated with subsequent VBA stroke.
CONCLUSION: VBA stroke is a very rare event in the population. The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.