Dear allstaters and experts in design issues,
A randomized controlled open label trial was set to compare contraceptive effectiveness of devices A and B for participants to prevent pregnancy and to compare its acceptability. At the time of study initiation, device A was known to have a shorter shelf life of 3 years while device B had a 5 years shelf-life. Initially the study was designed for three years and participants accepting to participate consented for this length of follow-up, which was the lifetime of use for device A. However during the folow-up of this study new scientific evidence showed that infact device A could be effective beyond 3 years, and upto 5 years. This evidence was used to extend the follow-up time for the study to 5 years, so that the outcomes could be evaluated at both the 3rd and the 5th year. The participants were asked for consent to extend their participation beyond 3-yrs upto the 5th year. Some participants did, and others did not.
My question is regarding the evaluation of the outcomes at the 3rd year, i.e the cumulative rate of method discontinuation by the 3rd year(which measures the acceptability of method A or B). I find that there is massive method discontinuation for device A at 3 yrs compared to device B. While understandably this may have to do with the participants lack of confidence in continuing using device A beyond 3 yrs, given their initial knowledge about the shelf-life of this device and may not necessarily have to do with its lack of acceptability of method. My question is at this 3-yr period, how, in terms of analysis can one be able to take this fact into consideration or separate this fact from the true effect of the two devices on acceptability?
Kindly send any responses directly to me.
Thanks in advance.
Ndema.
You may leave the list at any time by sending the command
SIGNOFF allstat
to [log in to unmask], leaving the subject line blank.
|