Compliance in a school-based caries clinical trial of a sugar-free chewing gum

There is currently little reliable and quantifiable compliance data reported for preventive trials of oral disease. During a two-year, school-based caries clinical trial of sugar-free chewing gum, strategies to promote compliance with a gum-chewing protocol were implemented and outcomes measured.

Over a 28-month period 2720 subjects, aged 11½-13½ at baseline, were recruited from 29 secondary colleges in Melbourne, Australia. Subjects were required to chew gum (test or control) for 10 min 3× daily, including once during a supervised school chewing session. The main compliance promotion strategies were regular school visits, regular provision of information and performance feedback and reimbursement. Compliance was measured using supervised school chewing logs, self-report paper diaries and returned unused home-use gum. The primary compliance outcome was the percentage of supervised school sessions attended by the subject over a 24-month period.

Overall supervised session attendance was 63.9 ± 17.6%. There was no significant difference between control and test groups in supervised session attendance. Average diary return rate was 76%, with final diary returns of 84%. Data from diaries were not considered sufficiently robust to analyse and report. The return rate for unused home-use gum was poor.

This research highlights the importance of: (1) dedicated compliance trial personnel in an adequate ratio to trial subjects; (2) inclusion in protocols of direct methods of measuring compliance; (3) prompt analysis of compliance data; (4) piloting of compliance data collection tools and (5) self-report paper diaries having questionable feasibility as a compliance data collection tool.