I work in a University Hospital, the only trials I have come across involve the training and examining of student doctors. Suitable patients are selected by consultants and asked if they would be willing to take part. These are always out patients, travelling expenses are paid and lunch is provided, the patients are interviewed by the student for 10 minutes only and the student then has to make a diagnosis from a brief examination and questioning the patient, obviously the patient already knows their diagnosis, but is not allowed to tell the student, only answer his questions. The student then goes on to the next patient. Usually there are about 20 students and 20 patients. This is part of the final examinations. The conditions' of the patients are usually chronic, ie. MS, ME ,chronic cardiac failure, IBS. Nurses also have to do case studies as part of their training but their focus is on care rather than diagnosis. Hope this answers your question. Judy