Table 2.

Summary of characteristics of included studies.

Reference	Patients, n	Gender (M:F)	Mean age	History of VTE	Follow-up	Surgery	Treatment	Mobilization after surgery (days)	Outcome
(17)	70	24:46	52.2	None	At POD 14 and POD 30	THA	Aspirin 100 mg bid: 34 patients (5 weeks); Rivaroxaban 10 mg qd: 36 patients (5 weeks)	POD1 (walk with crutch assisted)	Evaluation with lower limb USG, 3 patients in both groups with distal DVT.
(18)	329	223:106	47	15	For 90 days	Trauma1	Aspirin 81 mg bid: 165 patients*; Enoxaparin 30 mg bid : 164 patients*	Not stated	90 days event-free in 99 patients in the aspirin group (59.9%) and 98 patients in the LMWH group (59.4%); No significant statistic difference within both group
(19)	3424	1637:1787	62.8	81	For 90 days	THA and TKA	Aspirin : 81 mg qd: Hip : 902 patients (30 days), Knee : 805 patients (9 days); Rivaroxaban : 10 mg qd: Hip :902 patients (30 days); Rivaroxaban : 10 mg qd : 815 patients (9 days)	Not stated	VTE occurred in 11 patients (0.64%) among aspirin group and 12 patients (0.70%) in rivaroxaban group (P < 0.001 for noninferiority and P = 0.84 for superiority).
(20)	120	9:111	64.4	None	For 6 weeks	TKA	Aspirin 100 mg qd : 60 patients (14 days); LMWH 5000 U/day, POD 1-5, continued with Rivaroxaban 10 mg qd (POD 6 -14)	POD1 (active-passive motion, walking with crane)	DVT in 10 patients (16.7%) when using Aspirin and 11 patients (18.3%) when using LMWH and rivaroxaban but no significant difference (P = 0.500)
(21)	324	80:244	64	None	For 4 weeks	TKA	Aspirin 100 mg qd : 110 patients (14 days); Rivaroxaban 10 mg qd : 102 patients (14 days); LMWH 4000 U qd : 112 patients (14 days)	POD 2 (walking with walking aids under the guidance of caregivers)	Incidence of DVT higher in Aspirin group versus Rivaroxaban (18 (16.36%) vs 3 (2.94%),P = 0.017)); No significant difference in DVT incidence with Aspirin compared to s.c. LMWH (14 (12.50%) vs 18 (16.36%), P = 0.831).
(22)	778	444:334	57.8	13	For 90 days	THA	Aspirin 81 mg qd : 380 patients (28 days); Dalteparin 5000 U qd : 398 patients (28 days)	Not stated	Venous thromboembolism was found in 5 of 398 patients among Dalteparin group and 1 of 380 patients among Aspirin group. Aspirin was found to be significantly non-inferior (P < 0.001) but not superior (P = 0.22) to Dalteparin.
(23)	900	328:572	63.8	Not stated	For 12 months	TKA	Aspirin 325 mg bid: 194 patients (4 weeks); Enoxaparin 40mg qd SC (2 weeks) + Aspirin 325 mg bid (2 weeks): 706 patients	POD 1	Symptomatic DVT occurs in 4 patients (2.1%) within the aspirin group and 15 (2.1%) within the LMWH group (P = 0.957).
(24)	275	99:176	68.9	None	For 4–-6weeks	TKA	Aspirin 325 mg bid + CCD: 129 (4 weeks); Enoxaparin 30mg bid (until discharge), 40mg qd (3 weeks)+ CCD : 135	Not stated.	The incidence of DVT for Aspirin (18/129) and Enoxaparin (17/135) was without significant difference (P = 0.34).

¹Extremity fracture proximal to the carpals or metatarsal, and hip or acetabular fracture;

^*Duration depends on hospital guideline.

CCD, calf compression device; THA, total hip arthroplasty; TKA, total knee arthroplasty,