Pérez de Llano 2003.

Methods	Study design: multicentre, prospective open study Method of randomisation: SAS statistics computer program Concealment of allocation: none Exclusions post‐randomisation: none Lost to follow‐up: none
Participants	Country: Spain. Setting: 3 hospitals. No.: enoxaparin 29, UFH 21 Age: enoxaparin mean 66.5 ± 16.2 years, UFH mean 65.9 ± 16.3 years Sex: enoxaparin 20 M/9 F, UFH 14 M/ 7 F Inclusion criteria: people diagnosed with pulmonary thromboembolism (PTE) diagnosed by ventilation‐perfusion scan or plethysmography Exclusion criteria: people with a previous DVT, PTE with haemodynamic repercussion, known factor of hypercoagulability, anticoagulant treatment, pregnancy, formal consideration for anticoagulation or serious concomitant illnesses
Interventions	Treatment: enoxaparin 1 mg/kg weight every 12 hours. Control: 5% sodium heparin 5000 IU initial bolus through an infusion pump adjusted to the partial thromboplastin time results to an approximated dose of 35,000 IU/day. Treatment duration: until a target INR of 2 to 3 was reached. Oral anticoagulation: acenocoumarol.
Outcomes	Primary: recurrence of DVT (if plethysmography showed a new venous region affected, if there was a proximal thrombus extension > 5 cm or if arteriography showed new intraluminal defects) or PE (if perfusion scan showed perfusion defects that had not existed in the initial exploration) and major bleeding (intracranial, retroperitoneal, requiring transfusion or haemoglobin < 2 or more points).
Notes	Follow‐up: 1, 3 and 6 months.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Patients were randomised from the lists of enrolled patients at each centre using the SAS statistics program". Comment: low risk of bias.
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not stated. Comment: insufficient information to permit judgement of low or high risk.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Not blinded for treatment allocation. Comment: given the clinical outcomes of the study, review authors judged that the non‐blinding of the participants and staff was unlikely to have affected the outcomes.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It is not stated whether the outcome assessors were blinded to treatment and therefore the risk of bias was deemed unclear.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All data accounted for.
Selective reporting (reporting bias)	High risk	Study authors discuss the length of hospital stay but it was not a prespecified outcome.
Other bias	Low risk	Study appears to be free from other sources of bias.