Commentary: The hormone replacement-coronary heart disease conundrum: is this the death of observational epidemiology?

Abstract

Under its definition for the word ‘hindsight’ the Oxford English Dictionary includes the following statement ‘hindsight is always better than foresight’ (http://dictionary.oed.com/), and the slogan of a private survey and evaluation company, ingeniously called Hindsight, is ‘remember hindsight is always 20/20!’ (http://www.hndsight.com/). We have the benefit of the ‘hindsight’ from randomized controlled trials (RCT) when we comment on this meta-analysis of observational studies, but whether the conflicting results between the trial and observational evidence on the association between hormone replacement therapy (HRT) use and coronary heart disease (CHD) will lead to 20/20 vision remains to be seen.