Comments were mailed back to the study investigators.
For the 68 cases included in the case-control study, questionnaires were mailed to 476 controls, of whom 81 % (384) responded.
Questionnaires were mailed separately to men and women.
Questionnaires were also mailed to patients who were unable to come to the extra visit and were asked to return the questionnaires by mail.
Endoscopies were captured from medical records mailed from the hospitals to the project secretary.
The baseline data before the treatments were collected by structured inter view, the follow-up data mainly by mailed self-administered questionnaires.
At the time that the interviews were scheduled, the proband and affected relative were told that they would be mailed a packet of self-rating assessments.
Each health center in the intervention group received a mailed report with their own baseline registrations as part of the implementation strategy.
