 The identity number on the anonymity card given by the health care professional to the patient was the only participant identifier for the different survey questionnaires thematic book and life-event calendar, medical questionnaire. The interviewer did not know the identity of the patient. No personally identifiable data was collected directly or indirectly for eligible individuals not offered participation or individuals refusing study participation. The general characteristics collected on the register among refusals were collected in the form of classes, and not precisely, thus not allowing for later identification. 