The authors advance the hypothesis that patients switched from atorvastatin to simvastatin are at greater risk of cardiovascular events and on this basis suggest that formal randomised trials are desirable. Their concerns around the potential implications of the current policy for switching statins would, if founded, have far-reaching consequences and therefore the study necessitates close scrutiny.
Grading of evidence
Case-control studies are the lowest grade of evidence among observational studies, the findings of which should always be referred to well-conducted randomised controlled trials where these are possible. This case-control study