Abbot 1997.

Methods	Site: Femoral to AK popliteal Study design: Multicentre RCT Method of randomisation: central randomisation, but exact method unclear Blinding: unblinded, intention to treat Exclusions post randomisation: not discussed Losses to follow up: high rate of losses to follow‐up (37 within first 12 months of follow‐up)
Participants	Country: USA Setting: multicentre No. of participants: 231 patients (240 limbs; 122 PTFE, 118 Dacron) Age: mean 67.1 yrs Sex: 145 male, 95 female Inclusion criteria: angiographically demonstrated superficial femoral artery occlusion with reconstitution of a popliteal segment above the knee Exclusion criteria: earlier infrainguinal vascular procedures Unclear whether patients had IC or critical ischaemia
Interventions	PTFE versus Dacron (diameter at discretion of operating surgeon)
Outcomes	Primary patency, secondary patency, peri‐operative complications
Notes	13 patients randomised but not described. Unclear how many patients had post‐op aspirin
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Patients were randomised centrally after eligibility was determined by the operating surgeon and informed consent obtained."
Allocation concealment (selection bias)	Unclear risk	Not specifically stated. Probably not done
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	High risk	37 patients randomised lost by 12 months
Selective reporting (reporting bias)	Low risk	All stated outcomes reported
Other bias	Unclear risk	Anticoagulation protocol not stated