Post 2001.

Methods	Site: Femoral to AK and BK popliteal Study design: RCT Method of randomisation: concealed randomisation using computer generated randomisation envelopes Blinding: unblinded, intention to treat Exclusions post randomisation: 3 (1%) Losses to follow up: 6 (2%)
Participants	Country: Germany Setting: hospital No. of participants: 203 (194 limbs analysed. AK: 65 PTFE, 76 Dacron, BK: 26 PTFE, 27 Dacron) Age (median): 66 yrs Sex: 155 males, 48 females Inclusion criteria: severe claudication, rest pain, tissue loss Exclusion criteria: infection, emergency surgery for acute ischaemia, distal anastomosis below anterior tibial origin, concomitant disease not expected to live past 3 years, contraindication to anticoagulants
Interventions	PTFE and Dacron (diameter at discretion of operating surgeon) Post‐op warfarin, heparin or antiplatelet agents
Outcomes	Primary patency 3‐year follow up
Notes	No consistent anticoagulation protocol. No compliance checks
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The order of Secondary end‐points assignment had been generated by random digits from a statistical software package (SAS)."
Allocation concealment (selection bias)	Low risk	Quote: "Patients were randomised to either treatment arm intraoperatively by sealed envelopes."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Operative blinding impossible in this type of trial
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome assessors and patients not obviously blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses, clear life table data
Selective reporting (reporting bias)	Low risk	All stated outcomes reported
Other bias	Unclear risk	No consistent anticoagulation protocol