Annual mailers to all surviving RBS participants began in 1977. There have been 32 annual mailers since follow-up began with response rates ranging from 65% to 93%. The mailers assessed a wide variety of information that varied from year to year. A questionnaire was included approximately every two years to gather updated data on current health and diseases (see Health Status Follow-up). The Mailer Summary Table provides an abbreviated list of mailer topics by data grouping and by year. For topic-specific data from mailers, see mailer data summaries for each data grouping where appropriate.