Prospective, controlled non-interventional cohort study with three arms: women using

1) drospirenone/estradiol [DRSP/E2],

2) other oral continuous-combined HRT, and

3) all other oral HRTs.

The combined cohorts will include at least 30,000 women aged 40 or older in five European countries (Austria, Germany, Italy, Spain, and the Netherlands) who started or switched to an oral HRT at the time of inclusion in the study. At least 90,000 years of observation are expected.

Field work started in early 2002 and will end around 2008. Recruitment is done by a network of approximately 1,000 gynecologist/primary care physicians.

Baseline and follow-up information are collected via a self-administered questionnaire.

A multifaceted 4-level follow-up procedure ensures low loss to follow-up rates.

Data analyses – with and without stratification – are based on life-table meth-ods, making allowance for confounding by methods that include multivariate techniques such as Cox regression.
The analyses will include

1) a comparison of incidence rates of serious or unexpected adverse events among users of the three cohorts, and

2) a description of the utilization of DRSP/E2 compared with other oral HRT formulations.