a series of pilot studies in which we first contacted the selected individuals by mail with follow-up by telephone, offering participation in the study at the closest hospitals of the catchment area. Then, we advertised the study on the local TV and in newspapers, and added gas coupons as reimbursement for time lost. Subsequently, we proposed conducting the interview in the subjects' homes, and added a letter endorsing the study signed by the family physician. These efforts achieved a response rate of 48.9%. To increase the participation rate further, we consulted with one of the largest market research companies in Italy, and implemented the following procedures: we altered the layout of the invitation letter, established a toll-free phone number through which potential participants could obtain study information, added to our invitation a letter from the mayor of Milan supporting our research project, and requested that family physicians call the subjects directly to inform them about the seriousness and scientific value of the study. We also provided a token of gratitude (gas coupon) to the physicians. With these measures, we achieved an acceptable response rate of 72%. Overall, in the pilot studies, we collected data on approximately 300 subjects. This level
