The HRT controversy: observational studies and RCTs fall in line.

摘要

For several years, we witnessed a disarraying debate about the conflicting messages between observational studies and randomised trials on the effect of hormone replacement therapy (HRT) on coronary heart disease and breast cancer. HRT seemed protective for coronary heart disease in observational studies, but randomised trials found an increase of coronary heart disease in the first years of use. For breast cancer, combined oestrogen-progestin showed a lesser risk in the large Women's Health Initiative randomised trial than in observational studies such as the Million Women Study. Unopposed oestrogens had a smaller breast cancer risk than combined preparations in observational studies, but carried no risk in the trial. Observational research suffered a credibility crisis.