Myers 1994.

Study characteristics
Methods	Allocation concealment: opaque, sequentially numbered sealed envelopes (arteries randomised) Blinding of outcome assessment: duplex blind, clinical FU not blind Cross‐overs: none Exclusions during trial: none Participants lost to FU: 6 patch, 8 no patch (11%)
Participants	Country: USA Number of participants: 109 Number of operations: 126 Sex: 99% male Mean age: 62 years % asymptomatic carotid disease: 23% % stenosis: unknown Comparability: age, sex, vascular risk factors and % asymptomatic disease similar in each group
Interventions	Treatment: saphenous vein patch Control: primary closure % shunted: routine shunt for all Medication: peri‐ and postoperative aspirin (325 mg) for all
Outcomes	Death within 30 days and during FU; stroke within 30 days and during FU; perioperative occlusion (ocular pneumoplethysmography); wound haemorrhage, infection or cranial nerve palsy; restenosis > 50% or occlusion at end of FU (duplex)
Notes	Exclusion criteria: ICA diameter < 5 mm, arteriotomy > 3 cm, looped or kinked ICA FU: 4 to 5 years Funding sources for the study: none reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Sequentially numbered (arteries randomised).
Allocation concealment (selection bias)	Low risk	Opaque sealed envelopes.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of study participants not reported. Because of the nature of the intervention (patch or primary closure), the surgeon could not be blinded.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of outcome assessment not reported.
Incomplete outcome data (attrition bias) All outcomes	High risk	11% of participants lost to follow‐up.
Selective reporting (reporting bias)	Unclear risk	Unclear whether study authors reported the results of all prestated outcomes.
Other bias	Low risk	None suspected.