Prevention

High-risk cases

Alternatives include anti-platelet drugs ^a (aspirin ^{a b} , dipyridamole, hydroxychloroquine, ticlodopine) 

Why?

• Anti-platelet drugs reduce venous thromboembolism in high-risk medical and surgical patients. The benefits are greater the more risky the surgery (traumatic orthopaedic > elective orthopaedic > general surgery) ^a
• However bleeds requiring transfusion or re-operation are more common. Wound haematoma and associated infection are also more common. ^a
• Pneumatic compression, LMWH and warfarin are more effective than aspirin at reducing symptomatic DVT following total knee arthroplasty. ^a
• There is no clear benefit from combining antiplatelet drugs with heparin or LMWH. ^d

Antiplatelet drugs reduces venous thromboembolism but increase bleeding

Patient a	Treatment	Comparison	Outcome	CER	OR (95% CI)	NNT (95% CI)
high-risk surgery	antiplatelet drug	placebo	DVT at 2 weeks	35%	0.39 (0.33 to 0.45)	11 (9 to 16)
			PE at 2 weeks	2.7%	0.64 (0.48 to 0.80)	58 (44 to 86)
high-risk medical	antiplatelet drug	placebo	DVT at 2 weeks	23%	0.42 (0.25 to 0.59)	13 (7 to 75)
			non-fatal bleed requiring transfusion at 2 weeks	0.39%	87 (0 to 250)	290 (150 to 16000)
			bleed requiring reoperation, wound haematoma, infection due to bleed at 2 weeks	5.6%	39 (12 to 74)	45 (27 to 130)
total knee arthroplasty	pneumatic compression	aspirin	symptomatic DVT  at days	53%	3.25 (2.7 to 3.8)	4 (4 to 4)
	LMWH	aspirin	symptomatic DVT  at days	53%	3.47 (3.04 to 3.96)	4 (3 to 4)
	warfarin	aspirin	symptomatic DVT  at days	53%	1.7 (1.5 to 1.9)	8 (7 to 10)