Harter 1979.

Methods	Study design: randomised, double‐blind, clinical trial
Participants	Country: United States No. of participants: 44 Age: aspirin 53 ± 14 years, placebo 46 ± 16 years Gender: M = 20, F = 24 Inclusion criteria: patients undergoing chronic haemodialysis Exclusion criteria: recent gastrointestinal bleeding
Interventions	Treatment: aspirin 160 mg/day Control: placebo Duration: aspirin or placebo started 1 month postoperation and continued for approximately 5 months
Outcomes	Primary: graft thrombosis
Notes	AV shunts
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not stated Unequal group sizes
Allocation concealment (selection bias)	Unclear risk	Insufficient data to assess
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Stated that participants and members of the study team were blinded to treatment assignment. Placebo and the study drug were provided by the same company
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient data to assess
Incomplete outcome data (attrition bias) All outcomes	Low risk	31 participants completed the study
Selective reporting (reporting bias)	Unclear risk	Pre‐study protocol not available
Other bias	Unclear risk	No pre‐specified enrolment value. Enrolment would continue until 24 thrombi were observed.