Zakarian 2004.

Methods	Country: USA Setting: community RCT
Participants	150 smoking mothers with children aged 4 or younger
Interventions	Principal investigator and project co‐ordinator met with medical directors from each clinic to plan investigation implementation, then regularly throughout the study to "enlist participation and ongoing support". Intervention: Seven behavioural counselling sessions (3 in‐person and 4 over the telephone) over 6 months. Mothers were assisted in developing plans to reshape their and other household members' smoking behaviours. Mothers were asked to use pictorial charts and to self‐monitor their smoking and exposure. If participants asked counsellor for help in quitting smoking, they were issued a "Quit Kit" from the American Cancer Society. Control: usual care and 3‐, 6‐, and 12‐month follow‐up measures
Outcomes	Mother report of smoking status and child's exposure to ETS Child urinary cotinine concentrations Air nicotine monitors
Type of intervention	Well‐child (child health check)
Notes	Retention: 128/150 (85%)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Assignment was stratified by child's age, ethnicity, gender, and clinic site. Random number lists were generated for each strata."
Allocation concealment (selection bias)	Low risk	"Within each group of four numbers corresponding to four participants in that strata, the first two even numbers were assigned to the experimental group."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Intention‐to‐treat analyses: "mothers who were lost to follow‐up and not measured were counted as smokers" 68/74 control and 60/76 intervention reached at final follow‐up
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Biochemical validation used "Research assistants who obtained measurements were blind to group assignment, and control families were unaware of counselling procedures."