General use of hormone replacement therapy (HRT) dropped drastically after 2002 when pivotal randomized trials showed increased risk of coronary artery disease and other complications with HRT. HRT is not recommended for primary or secondary prevention of coronary heart disease and guidelines recommend discontinuation of HRT after myocardial infarction (MI). It is unknown whether women actually discontinue HRT after MI. Women who use HRT when they experience their MI generally continue using HRT. We found a remarkably low increase in discontinuation after 2002, in contrast to the general drop in use of HRT. To characterize the pattern of use and discontinuation of postmenopausal hormone replacement therapy (HRT) in women with myocardial infarction (MI) before and after 2002, where the general use of HRT dropped drastically subsequent to the results of the Women's Health Initiative trial. All Danish women aged ≥40 years hospitalized with MI in the period 1997 to 2005 and their use of HRT were identified by individual-level-linkage of nationwide registers of hospitalization and drug dispensing from pharmacies. Characteristics associated with HRT use at time of MI and subsequent HRT discontinuation were analysed by multivariable logistic regression. In the study period, 34,778 women were discharged after MI. Of these, 3979 (11.4%) received HRT at the time of MI and their most used categories of HRT were vaginal oestrogen and oral oestrogen alone (46.6% and 28.7%, respectively). The percentage of women who continued HRT during the first year after discharge was 85.0% in the period 2000-2002 and had decreased to 79.6% in the period 2003-2005. Vaginal oestrogen use was associated with overall discontinuation of HRT (odds ratio [OR] 1.37, 95% confidence interval [CI] 1.10, 1.72), whereas use of oral oestrogen alone and use of oral cyclic combined oestrogen/progestogen were associated with change of HRT after MI (OR 2.33, 95% CI 1.10, 4.93 and OR 2.94, 95% CI 1.35, 6.39, respectively). The majority of women experiencing an MI during ongoing HRT continued HRT after discharge and this pattern of HRT use did not change markedly after 2002. © 2010 The Authors. British Journal of Clinical Pharmacology © 2010 The British Pharmacological Society.
