Erler 1991.

Methods	Study design: 2 parallel arms, randomised, double‐blind. Method of randomisation: block randomisation. Exclusion post randomisation: not reported. Losses to follow up: not reported. Quality score = 3.
Participants	Country: Germany. Setting: hospital. No: 40 entered, drop outs not reported. Age: (mean) 55.5 and 53.9 years in treatment and control group, respectively. Sex: males 10; females 20. Inclusion criteria: oedema due to CVI. Exclusion criteria: oedema due to other conditions than CVI, vasoactive medication, compression treatment, venous ulcers.
Interventions	Treatment: 1 capsule HCSE (standardised to 75 mg escin) twice daily. Control: O‐beta‐hydroxyethyl rutosides (2 g daily). Duration: 8 weeks.
Outcomes	Primary: circumference before and after oedema provocation. Secondary: (not explicitly defined) symptoms (leg pain, oedema, pruritus, fatigue).
Notes	Standardised mean difference (95% CI): Primary: Not enough data provided for effect size calculation. Secondary: Not enough data provided for effect size calculation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	Allocation concealment not reported
Blinding (performance bias and detection bias) All outcomes	Low risk	Neutrally coated capsules which were indistinguishable in terms of outer appearance
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	It is unclear how incomplete outcome data were addressed
Selective reporting (reporting bias)	Low risk	No evidence of selective reporting
Other bias	Unclear risk	No evidence of further biases