Background:
Second-hand smoke exposure puts children's health at risk. Among other conditions, such children can acquire respiratory tract infections, asthma and tuberculosis. Our purpose was to pilot an educational intervention for primary school children - Smoke Free Intervention - and to assess the feasibility of recruiting, randomizing, and measuring outcomes in a definitive trial.

Methods:
We conducted a large pilot cluster randomised controlled-trial in primary schools in Dhaka, Bangladesh. It recruited Year-5 children (10-12 years old) and randomly allocated eligible schools to either Smoke Free Intervention (intervention arm) or to normal lessons (control arm). Participating children, schoolteachers, and researchers could not be masked from the treatment allocation. In the intervention arm, schoolteachers delivered two 45-minute educational sessions and four 15-minute refresher sessions over four weeks. Our primary outcome was second-hand smoke exposure validated by salivary cotinine. Secondary outcomes included respiratory symptoms, lung function tests, school attendance, smoking uptake, and academic performance. We based our primary analysis on intention-to-treat. The trial registration number: ISRCTN68690577.

Results:
Between April 01, 2015 and June 30, 2015, we approached 25 schools and recruited 12. Out of 576 children in year-5 in these schools, 484 were present on the day of trial recruitment; 481 consented. Six schools (245 children) were allocated to the Smoke Free Intervention arm and six (236 children) to the control. All 12 schools were retained, however, 91.4% children (224/245) in the Smoke Free Intervention arm and 88.6% (209/236) completed their first follow-up. Two-months after allocation, salivary cotinine at the cluster level was 0.53 ng/ml (SD 0.36 ng/ml) in the intervention arm and 1.84 ng/ml (SD 1.49 ng/ml) in the control arm.

Conclusions:
It is feasible to recruit, randomize and retain primary schools and children in a trial of this nature. The effectiveness of Smoke Free Intervention should be tested in a fully powered randomized controlled trial.