Once data is collected by fieldworkers, the completed questionnaires will be brought to the headquarters of the study, where supervisors will check for potential mistakes or missing information. Investigators will use a case report form per participant, where a checklist of all information to be collected from them and the quality of it, will be recorded. The case report form will be filled out by the field supervisor every time is checking the file of each subject. The purpose of the case report form will be for monitoring the quality of the information collected, and to check that all the information is being collected on time.