Methods	Cluster RCT, with the institution as the unit of randomisation
Participants	Obstetricians from 27 tertiary care hospitals. (One hospital withdrew post randomization); Intervention: n=13 and Control: n=14 Country: US Type of targeted behaviour: general management of a problem (foetal maturation)
Interventions	Intervention Local Opinion Leaders + audit & feedback + chart reminder + clinical guideline + grand round. Method of OL identification: Informant Proportion of social network that nominated OL: N/A Single OL or OL teams identified: teams of two persons (one nurse + one physician) OL disseminated information: Informal OL frequency of involvement: UNCLEAR Control Standard dissemination of clinical guideline
Outcomes	Appropriate use of antenatal corticosteroids for foetal maturation
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Pg. 47/Col 3/Para 2 We assigned hospitals by random number table either to the active dissemination (n= 13) or usual dissemination control (n=14) group
Allocation concealment (selection bias)	Low risk	It was a cluster RCT, with the institution as the unit of randomisation
Blinding (performance bias and detection bias) All outcomes	Unclear risk	p.47/Col 3/para 2 and p.48/Col 1/Para 1 “The study was not blinded because physicians in the active dissemination condition were aware of the situation, and the leadership of all hospitals were aware of the condition of assignment”
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?	Low risk	Pg.50/Table 1
Similar baseline characteristics?	Low risk	Pg, 49/Col 3/ Para 2 There were no baseline differences between intervention and control hospitals for the following characteristics: geographic region, median number of Active obstetricians, births per hospital, NICU beds, percentage Medicaid patients, race, PROM diagnosis, GA, and indicated deliveries. Hospital characteristics were generally the same in both the NPIC and AECOM hospitals. A difference between intervention and control cases in the frequency of abnormal fetal conditions or fetal distress was significant at the patient level due to the large sample size
Protection against contamination?	Low risk	Pg. 47/Col 2/ Para 1 “To avoid diffusion of the active dissemination treatment to the control group, the unit of randomisation was the hospital.”