Zhu 2012.

Methods	Setting: Quitline, USA Recruitment: Callers to a quitline
Participants	2278 Chinese‐, Korean‐ and Vietnamese‐speaking daily smokers, ready to quit within 1 m; 90% M; aged 18 ‐ 75 (approx. 45% 25 ‐ 44 and 45% 45 ‐ 64); av. cigs/day 15.6
Interventions	1. S‐H pack, culturally‐tailored, translated into Chinese, Korean and Vietnamese 2. S‐H pack + proactive TC; Social Learning Theory; MI; CBT techniques. 30 ‐ 40 mins, pre‐quit, up to 5 relapse prevention calls (10 ‐ 15 min) 0, 3, 7, 14, 30 days
Outcomes	Prolonged abstinence at 7 m post‐intervention, 1 m grace period immediately post‐quit Validation: none (but saliva samples collected)
Notes	Number abstinent at 6 m not specified; data used in MA calculated back from percentages
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "randomly assigned…using blocks of 20 to keep a balance of language and sex…Random assignment tables for each strata were created using SAS 9.2."
Allocation concealment (selection bias)	Low risk	Quote: "The allocation was done by the computer so that staff were blinded to group assignment until the intake call"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Self‐reported outcomes but saliva samples collected. No statistically significant differences in saliva sample return rates at 7 m between intervention and control groups and between self‐reported quitters and non‐quitters
Incomplete outcome data (attrition bias) All outcomes	Low risk	Simlar rate of dropouts in both groups (18% in 1, 16% in 2). Participants lost to follow‐up included as smokers in outcome data