Νομιζω ανοιχτή μελέτη η ανοιχτή κλινική μελέτη ;
Please take this with a grain of salt.
There's a couple of references/articles on the net if you google search with the key words ... rollover study and drugs.
Unfortunately they don't offer satisfactory explanations and do not explain what the term means (it's as if the articles are aimed at trial clinicians who understand the term) but from what I gather I think a rollover study may refer to a study conducted during the final stage or stages of a drug trial,
So the safety and dosage levels may have already been determined at an earlier trial phase and some blind/placebo tests would also have been conducted... so a a lot has been learned about the drug, before the rollover study stage is reached.
I think that in the final rollover stage the patient/trial participant is told about the drug and how it works etc.., he/she knows that the actual drug has been administered to him/her (i.e.that they definitely didn't get a placebo) and this rollover study may also follow whether the patients are satisfied with the drug, if they adhere to taking it as prescribed (or whether they may decide to stop taking the drug) and also perhaps provides the opportunity to gather some additional information,e.g. the patient serum level responses over an extended time period and feedback from the patients etc..