Adrian Wenban, B.Sc., B.App.Sc., M.Med.Sc
Journal of Vertebral Subluxation Research ~ September 2001 ~ Volume 4 ~ Number 3 ~ Pages 68-74
Observational research suggests that there may exist an association between neck manipulation and stroke.
Although the issue of harm is best studied using randomized trials, the rarity of such accidents often make the use of that design impossible. As a result, whether an association exists between an intervention and harmful side-effects is often assessed with controlled observational studies (cohort and case-control studies).
This article aims to provide a guide for practicing chiropractors on how to assess the validity of case-control studies concerning harm. Furthermore, this article provides a guide on how to assess the extent to which causal inferences can be made from such studies. The example used is the possible relationship between chiropractic adjustments and stroke.
This article is structured through the use of two critical appraisal guidelines, the likes of which are widely promoted and used by the proponents of Evidence-based Medicine. The guidelines propose a series of questions and criteria that allow the different research designs used in studies reporting an association between neck manipulation and vertebrobasilar accidents(VBA’s) to be critically appraised.
The critical appraisal of a study concerning harm is best achieved using a structured guideline that facilitates assessment of the validity of individual papers and consideration of the extent to which causal inferences can be made. There is no human experimental evidence that chiropractic adjustments, or neck manipulations, are causally related to VBA’s. The strength of the inferences that can be made from observational studies carried out to date are severely limited by design issues. Although there may exist a weak association between neck manipulation and VBA’s we know very little about the nature of that relationship. The recent publication of a case-control study by Rothwell et al. provides little insight into whether a causal relationship exists between chiropractic adjustments and VBA’s.