Rasmussen 2006.

Methods	RCT, assessor blinded, venography.
Participants	Patients undergoing major abdominal surgery for either malignant or benign diseases.
Interventions	LMWH (dalteparin 5000 IU, total treatment period 28 days) or no treatment.
Outcomes	LMWH 165 Control 178
Notes	Follow‐up period 3 months. Complete follow‐up. All patients were scheduled for bilateral venography. Adequate definitions of VTE and bleeding complications were described in the paper. Venography performed on day 28.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated allocation list.
Allocation concealment (selection bias)	Unclear risk	Unclear.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Open‐label study with assessor‐blinded evaluation of the venograms. Patients, healthcare providers and data‐analysts were not blinded.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open‐label study.
Incomplete outcome data (attrition bias) All outcomes	High risk	Forty‐four (19.8%) patients in control group and 40 (19.5%) patients in experimental group excluded.
Selective reporting (reporting bias)	Unclear risk	Modified intention‐to‐treat analysis of patients reaching an evaluable VTE end point (venogram or objection verification of symptomatic VTE).
Other bias	Low risk	The study appears to be free of other sources of bias.