We examined whether the discrepancy between observational studies and randomized clinical trials (RCTs) on the effect of hormone replacement therapy (HRT) on myocardial infarction (MI) could be explained by differences in age of participants at the time of either HRT initiation or the MI event.
Medical Statistics Unit, Department of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK. joseph.kim@lshtm.ac.uk