It is interesting to hear about this study and seems quite large. What kinds of measures are you using at the different time points? You were correct, I am interested in the data analysis portion and some of the ways in which you track change over time.
With respect to your comment about a "true" outcome assessment, I think a prospective analysis is clearly preferable to not having any baseline assessment. However I don't think that the prevailing model of assessing outcome (tracking patients post-intervention) actually does allow the researcher to ever know whether it is treatment outcome we are assessing, given the lack of a control group. However patients can serve as their own controls and with large enough numbers and longitudinal tracking, it becomes easier to feel comfortable to assert that the changes noted are indeed related to intervention. Just a thought...
If you don't mind sharing more about your study it is most helpful. Looking forward to more discussion.