The Oxford Levels of Evidence are now routinely assigned at many orthopaedic journals. One disadvantage of this approach is that study designs with a higher level of evidence may be given greater weight than the overall quality of the study merits. In other words, there is no guarantee that research is scientifically valid simply because a more sophisticated study design was employed. The aim of this study was to review Level-I and II therapeutic studies on lateral epicondylitis to measure variation in quality among the highest-level study designs. It was found that the use of the gold-standard trial design, the prospective randomized therapeutic study (Level-I or II evidence), does not ensure quality research or reporting (1). Critical analysis of scientific work is important regardless of the study design. 

A quantitative score based on the Bradford Hill criteria was used to evaluate 117 articles presenting original data regarding the etiology of carpal tunnel syndrome (2). According to a quantitative analysis of published scientific evidence, the etiology of carpal tunnel syndrome is largely structural, genetic, and biological, with environmental and occupational factors such as repetitive hand use playing a minor and more debatable role. Speculative causal theories should be analyzed through a rigorous approach prior to wide adoption. 

References

1. Cowan J, Lozano-Calderon S, Ring D. Quality of prospective controlled randomized trials. Analysis of trials of treatment for lateral epicondylitis as an example. J Bone Joint Surg Am. 2007;89(8):1693-9.
2. Lozano-Calderon S, Anthony S, Ring D. The quality and strength of evidence for etiology: example of carpal tunnel syndrome. J Hand Surg [Am]. 2008;33(4):525-38.