It's a good thing. I participated as a principal site investigator in numerous clinical drug trials in Phases 2 and 3 and 4 (post approval studies) and am well aware of the importance of proper screening of patients for selection in multi-year clinical trials. In such long term studies lasting multiple years like the rollover study, it is critical to enroll compliant patients committed to follow up appointments over the entire length of the trial. This requires screening those enrolled in the ongoing trials from which the rollover trials are receiving their patients, for those people most likely to res9de in geographic areas close to clinical trial sites for the duration of the study and are currently in sufficient good health to complete the trial lasting so many years. (In my experience the best compliance with long term trials tends to be in Europe where patients do not change geographic locations where they live as often as they do in the US.) Screening patients may afford some assessment of suitability for patients likelihood of finishing the trial, since drop outs lower the power of the statistical significance of the trial when final data is analyzed after trial completion.