Healthy Skepticism Library item: 17902

Warning: This library includes all items relevant to health product marketing that we are aware of regardless of quality. Often we do not agree with all or part of the contents.

Publication type: Journal Article

Mayor S
Researchers claim clinical trials are reported with misleading statistics
BMJ 2002 Jun 8; 324:(7350):1353
http://www.bmj.com/cgi/content/extract/324/7350/1353/a

Abstract:

US researchers have claimed that most randomised trials of new treatments published in leading medical journals are reported in a potentially misleading way, with statistics designed to make the results more positive than if other statistical tests were used.

Researchers from the University of California at Davis, near Sacramento, reviewed 359 randomised clinical trials of new treatments published between 1989 and 1998 in five major medical journals: the Annals of Internal Medicine, BMJ, JAMA, Lancet, and New England Journal of Medicine.

They found that most of the trials report results based on relative risk reduction—-the percentage difference in end points between the active treatment and the placebo or comparison treatment. The study showed that only 18 of the papers reviewed considered absolute risk reduction—-the actual difference between the treatment and placebo results. Only eight of the 359 trials reported the number needed to treat—-the number of patients needed . . .