Stephen J.LurieMD, PhD, Senior EditorIndividualAuthorPhil B.FontanarosaMD, Executive Deputy EditorIndividualAuthor
In Reply: Dr Shah suggests that systematic
reviews of observational studies provide better evidence than single randomized
trials. We disagree strongly. Shah's proposal would, for instance, rank a
meta-analyses of observational studies of hormone replacement therapy1 (which suggested a 50% reduction in relative risk
of coronary events) higher than the Heart and Estrogen/progestin Replacement
Study (HERS) RCT,2 which found no effect
of hormone replacement therapy for secondary prevention of coronary events.
We would rank the HERS RCT higher and, pending further RCT evidence, would
not recommend hormone replacement therapy to women to decrease their risk
of cardiovascular events. When consistent biases exist in observational studies
(such as the tendency for women with lower cardiovascular risk to receive
hormone replacement therapy), a meta-analysis offers no protection.
Guyatt GH, Naylor D, Richardson WS, Green L, Haynes RB, Wilson MC, Cook DJ, Jaeschke RZ. What Is the Best Evidence for Making Clinical Decisions?—Reply. JAMA. 2000;284(24):3127-3128. doi:10.1001/jama.284.24.3123