Klesges 2006

Methods	Setting: Air Force, USA Recruitment: recruits undergoing basic military training (BMT)
Participants	Subgroup of ˜7525 regular smokers in intervention and ˜2639 in control
Interventions	1. Two 1 hour sessions during week 6 of BMT, emphasis on discrepancy between Air Force ideals and smoking. Barriers, role‐playing. One sheet of NRT gum available for use at end of training 2. Same schedule, health‐related and first aid videos
Outcomes	Abstinence at 1 year (sustained from end of BMT) Validation: none
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Cluster‐randomised by training flight. 75% assigned to intervention, method of sequence generation not specified
Allocation concealment (selection bias)	Low risk	Not specified, but training flight allocation was independent of this trial, so potential for bias small
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not specified
Blinding of outcome assessment (detection bias) All outcomes	High risk	Staff who conducted follow‐ups were not blinded to treatment assignment at follow‐up; differential follow‐up possible for participants who did not respond to survey and were contacted by telephone
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Random subgroup targeted for follow‐up, 86% reached. People lost to follow‐up excluded because likely to be missing completely at random