Prevention

High-risk cases

• low molecular weight heparin ^a e.g. 40 mg enoxaparin daily. ^a

Why?

• Both heparin and low-molecular weight heparin reduce DVT in elderly patients after surgery for proximal hip fractures  ^a
• LMWH is better than unfractionated heparin for preventing venous thromboembolism in general surgery, orthopaedic and trauma patients. ^a   It reduces wound haematomas, but has no clear effect on major bleeding. ^a   Around 2% of patients on LMWH have a major bleed. ^a
• LMWH is more cost-effective than heparin in high-risk cases. ^b
• 40 mg of enoxaparin daily reduces more DVT than lower doses but increases the risk of bleeding. Higher doses are not clearly more effective. ^a

LMWH prevents more DVT and PE than heparin in patients having orthopaedic or general surgery

Patient	Treatment	Comparison	Outcome	CER	OR (95% CI)	NNT (95% CI)
general surgery a	LMWH	heparin	DVT at discharge	6.7%	0.79 (0.65 to 0.95)	33 (23 to 87)
			PE at discharge	0.44%	0.44 (0.21 to 0.95)	260 (180 to 2800)
orthopaedic surgery	LMWH	heparin	DVT at discharge	21%	0.68 (0.54 to 0.86)	15 (10 to 34)
			PE at discharge	4.1%	0.43 (0.22 to 0.82)	43 (31 to 140)

LMWH prevents more DVT than heparin in trauma patients

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
Major trauma a	enoxparin for 14 days	heparin for 14 days	DVT	35%	33% (5% to 52%)	9 (5 to 56)

40 mg of enoxaparin prevents more DVT, but causes more major bleeding than 10mg

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
Undergoing hip replacement a	enoxparin 40mg daily	enoxparin 10mg daily	DVT at 7 days	25%	44% (10% to 77%)	9 (5 to 39)
			major bleed at 7 days	5%	-120% (-100% to -10%)	-17 (-200 to -9)