PRoFESS.

Study characteristics
Methods	Randomised. Allocation concealment
Participants	1360 participants (884 men and 476 women) with a history of stroke. Age of participants was greater than 55 years. Participants had to be hospitalised with stable stroke. 5 of 672 participants in the combination group (aspirin + extended‐release dipyridamole) and 7 of 688 participants in the clopidogrel‐only group were lost to follow‐up. 36 participants complained of headache in the combination group, whilst 3 participants in the clopidogrel‐only group reported adverse effects.
Interventions	Aspirin 25 mg twice daily plus extended‐release dipyridamole 200 mg twice daily vs clopidogrel 75 mg alone once daily followed for 90 days
Outcomes	Primary outcome: mRS at 30 days Secondary outcome: recurrent stroke, haemorrhagic transformation
Notes	Subset of participants enrolled early
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Methods described.
Allocation concealment (selection bias)	Low risk	Methods described.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blind
Incomplete outcome data (attrition bias) All outcomes	Low risk	12 of 1360 participants (0.8%) lost to follow‐up
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes reported