Kiil 1981.

Study characteristics
Methods	Allocation: random Double blind Exclusions after randomisation: 1 Losses to follow‐up: nil
Participants	Country: Denmark Participants: 20 Age: 17 to 79 years Sex: Male and female Inclusion criteria: venographically confirmed DVT duration < 72 hours Exclusion criteria: not described
Interventions	Treatment: urokinase 200,000 U IV over 24 hours. After 18 hours, heparin loading dose of 15,000 units then 40,000 U/day for 5 days Control: heparin 40,000 U/day IV for 6 days Co‐treatment: not described
Outcomes	6 days: clot lysis; bleeding 2 weeks: mortality
Funding	Not reported
Declaration of interests	Not reported
Notes	1 excluded from heparin group due to bleeding. Low dose urokinase. Did not specify whether calf vein thrombosis was included
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"....randomly separated" but no further details given
Allocation concealment (selection bias)	Unclear risk	"...allocation of the patients ... was performed by one of the participants" no further details given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"....mixture of liquids to be infused was performed by one of the participants"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	".....clinical evaluation and interpretation of phlebograms were preformed in a double‐blind fashion"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Exclusions explained
Selective reporting (reporting bias)	Low risk	All outcomes reported
Other bias	Low risk	None