Bollinger 1977.

Study characteristics
Methods	Study design: double‐blind, randomised Country: Switzerland Setting: single centre Intention‐to‐treat: not mentioned
Participants	Number of participants randomly assigned: 26 Number of participants analysed: 19 Exclusions postrandomisation: 0 Losses to follow‐up: 7 Age (mean): pentoxifylline: 63.9 years, placebo: 59.6 years Sex: pentoxifylline: 9 male, 1 female, placebo: 8 male, 1 female Inclusion criteria: IC (Fontaine stage II) Exclusion criteria: malleolar arteries could not be compressed by a cuff (mediasclerosis)
Interventions	Treatment: oral pentoxifylline, 200 mg tid Control: placebo Duration: 8 weeks
Outcomes	Primary: mean TWD Secondary: ABI
Notes	Treadmill protocol: 3.2 km/h at 12.5% inclination Mean TWD expressed in metres only Participants were instructed to refrain from smoking during the study and to walk daily for ≥ 1 hour
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "allocated at random to receive treatments." Comment: no other information provided.
Allocation concealment (selection bias)	Unclear risk	Not mentioned.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Both pentoxifylline and placebo were presented in identical tablet form and supplied in containers of 40 tablets, identified only by a code number."
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No incomplete outcome data.
Selective reporting (reporting bias)	Unclear risk	Protocol not available; insufficient information available to permit judgement.
Other bias	High risk	Differences in clinical baseline data between treatment groups.