Riley 2011.

Study characteristics
Methods	Cluster‐randomised trial comparing a combination of simulation and didactics, didactics only, and no intervention.
Participants	All employed multi‐professional labour and delivery staff members: 36 (simulation) versus 60 (didactics only) versus 38 participants (control)
Interventions	2‐3 hours didactics versus didactics combined with simulation‐based team training (in situ) versus no intervention. Training content: condensed TeamSTEPPS curriculum (used simulated scenarios: uterine rupture, placental abruption, postpartum haemorrhage)
Outcomes	Patient outcome: perinatal morbidity and mortality (weighted adverse outcomes scores). Culture of safety. Follow‐up: approximately 12 months.
Notes	Multicentre study including 3 hospitals, USA. Study period: 2005‐2008.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation type not described in manuscript/reported in correspondence.
Allocation concealment (selection bias)	High risk	Randomisation type not described in manuscript/reported in correspondence. Besides, as there were only 3 study groups and 3 clusters, allocation might have been foreseen.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Patients (outcome measure) were probably unaware of study allocation. Blinding of participants was not possible, however probably unlikely to affect outcome measures.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Data‐collectors were local personnel of participating hospitals. Data‐analyst might have been blinded (from correspondence).
Incomplete outcome data (attrition bias) All outcomes	Low risk	No clusters lost to follow‐up. From correspondence quote: "We had no missing data. All data were downloaded from the medical record." Although not mentioned in the manuscript, probably low risk of attrition bias.
Selective reporting (reporting bias)	Low risk	No not reported outcomes. No published study protocol available.
Other bias	High risk	High risk on performance bias as the simulation group received the TeamSTEPPS curriculum within the context of a clinical scenario, while the didactic group received no information about these scenarios. Clustering has not been taken into account.