Dear All,  I am quite new to the cdisc world, and have some questions that you may think trivial.  Any comments and suggestions would be greatly appreciated!  Thanks!  James Zhou

1. Definition of Arms

Our study is a dose-escalating Phase 1 trial, should we use dose to define arm?  There are many scenarios of doses.  Do we have to list of all possible doses as proposed in the protocol or just those actually administered to patients in the study? In addition, a patient could have different doses during the study.  How do we code the arm for these patients, defining a unique arm with mixed dosing?  In addition, a patient could have various number of dosing/cycle (defined below).  How do we incorporate this into the arm?

2. Definition of Elements:

In our study, a patient will basically go through following stages: screening, dosing, end of treatment and follow-up.  In dosing stage, there are lots of scenarios, such as: transitioning to different doses, transitioning to extra rest periods due to AE, various number of repeated dosing.  What's the best way to define elements in this case?

3. Definition of Visits:

In our study, a treatment cycle is defined as an interval of two weeks with first 5 days being treated with the drug everyday, and the next 9 days to followup.  A patient could be examined in any study days for lab, VS, etc, and also a patient could have more than more cycles.  We propose using the cycle to code for VisitNum.  Is this sufficient even there are multiple days of examinations within a single cycle?  If so, is it required to code dy variable in the study datasets?