Methods	Cluster RCT, with the hospitals as the unit of randomisation
Participants	Obstetricians, family practitioners and nurse midwives from 18 hospitals. Intervention: n=9 and Control: n=9 Country: US Type of targeted behaviour: mothers’ intention to breast feed during the early postpartum period
Interventions	Intervention Local Opinion Leaders + audit & feedback + formal meetings + printed educational material. Method of opinon leader identification: both sociometric (Coleman et al. - If you wish to discuss practice questions with other clinicians in your hospital, on whom would you most likely call?) and Informant (opinion leaders in the study were nominated also by the obstetric nurse-manager). Proportion of social network that nominated OL: 56% Single OL or OL teams identified:single OL OL disseminated information: Formal OL frequency of involvement:2 hours monthly Control Standard dissemination
Outcomes	Mothers’ intention to breast feed
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Pg 414/Col 2/ Para 2 We randomly allocated hospitals between intervention and control groups and conducted the 1-year opinion leader intervention
Allocation concealment (selection bias)	Low risk	It was a cluster RCT, with the hospitals as the unit of randomisation
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not mentioned in the paper
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not mentioned in the paper
Selective reporting (reporting bias)	Low risk	All outcomes mentioned in the methods section were also presented in the results
Other bias	Low risk
Similar baseline outcome measures?	Unclear risk	Unclear if the baseline outcome measures are similar.
Similar baseline characteristics?	Unclear risk	Mentioned that the characteristics did not differ but did not report baseline data
Protection against contamination?	Low risk	Pg 415/ Col 2/ Para 1 As the setting where obstetric providers interact, the hospital was the appropriate unit of randomisation. To avoid contamination among Binghampton and Syracuse clinicians with admitting privileges at multiple hospitals in those cities, we treated as one unit for randomisation the three hospitals in the Syracuse area versus the two in Binghampton and one in the surrounding area We matched the18 remaining hospitals on characteristics that might affect breast feeding or avoided contamination of the control group by clinicians in the intervention group