The intervention provided was both active medication that contained the hormones estrogen and progestin in a specific formulation and since this was a controlled trial a placebo was included and both the medication and the placebo were given to the patients according to the randomization. With respect to the outcomes, the study focused on the occurrence of any CHD events which was the primary outcome of the trial. The secondary outcomes such as coronary artery bypass and coronary revascularization were also studied during the follow-up period for every participant.
The study was randomized to ensure that there was no bias in the allotment of the medication and placebo to the participants and that every participant had an equal chance of being allotted either the active medication or the placebo. When a control is included in a trial it would help to determine the exact efficacy of the medication or therapy. With respect to this trial the RCT approach is completely justifiable. The randomization procedure was ensured to be tamper-proof and balanced by using the blocked randomization stratified procedure.
The included women were assigned according to computer generated randomized numbers to the intervention and control groups. However the exact method of allocation was not explained in detail. Both the groups were well balanced. The study was a single-blinded study as with the exception of the data analyses team the rest of the center staffs were blinded to participant assignment. This is quite evident as reports of the patients were submitted to a gynecologist who was located outside the center.
Only in defined and limited cases the study center gynecologists were referred and even that was done using sealed treatment envelopes. Such a level of unblinding, considering the circumstances, could be permissible. The duration of the study was for a four year period from 1994 to 1998 and follow-up
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