2.2.1. Letter Reminder
A reminder was mailed to the participants’ home addresses. The main components of the letter were an “explanation of the specific health guidance (including information that the specific health guidance was free of charge)”, “the expiration date of the specific health guidance”, “information on the medical centers/hospitals/clinics where the specific health guidance is provided”, and “telephone number for inquiries”. The expiration date was determined according to the month in which the participants underwent a health checkup. The coupon for specific health guidance was valid for two months from the time of dispatch.