Medical Study: Don’t Trust Medical Studies
A new study (“Scientific Evidence Underlying the ACC/AHA Clinical Practice Guidelines” by Pierluigi Tricoci; Joseph M. Allen; Judith M. Kramer; Robert M. Califf; Sidney C. Smith Jr) in the prestigious Journal of the American Medical Association, in Stuart Buck‘s words, “analyzes more than two decades of heart care guidelines (that is, the guidelines that your doctor might follow in deciding how to treat you) from the American College of Cardiology and the American Heart Association. The study found that the overwhelming majority of recommendations are not supported by good evidence.”
I don’t have access to the article but Stuart provides the following quote:
Level of evidence provides the link between recommendations and evidence base. Although there is significant variation among individual guidelines in available evidence supporting recommendations, the median of level of evidence A recommendations [i.e., those supported by more than one randomized trial] is only 11% across current guidelines, whereas the most common grade assigned is level of evidence C, indicating little to no objective empirical evidence for the recommended action. . . . Interestingly, our findings are reflective of a specialty — cardiology — that has a large pool of research to draw on for its care recommendations. Guidelines in other medical areas in which large clinical trials are performed less frequently may have an even weaker evidence-based foundation. [emphases original]]
This, from the abstract, is even more damning:
Recommendations issued in current ACC/AHA clinical practice guidelines are largely developed from lower levels of evidence or expert opinion. The proportion of recommendations for which there is no conclusive evidence is also growing. These findings highlight the need to improve the process of writing guidelines and to expand the evidence base from which clinical practice guidelines are derived.
I’ve noted for years that the standards for publication in medical journals are far less rigorous than for publication in social science journals. This, despite the former being far more important and the widespread perception that the latter isn’t really science at all.