Table 1

Evidence table of the 12 studies included in the meta-analysis

Study name	Study design	Intervention	Open, MIS, or mixed	Dose and timing	Post-op duration	Control	Sample size (n)	Outcome (DVT, PE, or both)	Benign or malignant	Quality
Ailawadi, 200118	Retrospective cohort	UFH+SCD	Mixed	5000 units on call to OR	Until discharge	SCD	168	Both	Malignant	High
Bouchard-Fortier, 201419	Retrospective cohort	UFH or LMWH	Mixed	Not noted	Mostly 2 doses or fewer	No prophylaxis	419	Both	Malignant	Poor
Clarke-Pearson, 198322	Retrospective cohort	UFH	Open	5000 units at midnight prior or 2 hours pre OR	Until POD 5–7	No prophylaxis or SCD	281	Both	Malignant	High
Corr, 201523	Prospective cohort	Pre-op UFH+SCD	Mixed	5000–7500 units prior to skin incision	Up to 14 days if malignant	Post-op UFH+SCD	527	Both	Both	High
Einstein, 200824	Prospective cohort	UFH+SCD	Not stated	5000 units 1–2 hours pre OR	Until discharge	SCD	605	Both	Both	High
Freeman, 201625	Retrospective cohort	UFH or LMWH+SCD	MIS	UFH 5000 units or enoxaparin 30–40 mg 1 hour pre OR	Until discharge	SCD	1143	Both	Malignant	High
Hansen, 200826	Prospective cohort	Pre-op UFH	Mixed	Dose not given; prior to skin incision	Not stated	Post-op UFH	9035	Both	Benign	High
Hopp, 201816	Retrospective cohort	Pre-op and post-op UFH+SCD	Not stated	Not noted	Not stated	Post-op UFH+SCD	1129	Both	Malignant	Poor
Maxwell, 20012	RCT	LMWH	Mixed	Dalteparin 2500 units 1–2 hours pre OR	Until POD 5 or ambulatory	SCD	211	Both	Malignant	Fair
Pelkofski, 201417	Retrospective cohort	Pre-op anticoagulant	Open	Dose not given; prior to skin incision	Not stated	Post-op anticoagulant	431	Both	Both	Poor
Ugaki, 200820	Retrospective cohort	Pre-op and post-op UFH+SCD	Open	2500 units 2 hours pre OR	1 dose 12 hours post-op	SCDs	85	PE	Malignant	Poor
Whitworth, 201121	Retrospective cohort	Pre-op LMWH and post-op LMWH+SCD	Open	40 mg 2 hours pre OR	Until discharge	Post-op LMWH+SCD	239	DVT	Both	Poor

*Mechanical refers to sequential compression devices or other mechanical venous thromboembolic prophylaxis.
DVT, deep vein thrombosis; LMWH, low molecular weight heparin; MIS, minimally invasive surgery; OR, operating room; PE, pulmonary embolism; POD, post-opereative day; post-op, post-operative; pre-op, pre-operative; RCT, randomized controlled trial; SCD, sequential compression device; UFH, unfractionated heparin.