Comparison 1. Heparin versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Symptomatic VTE (DVT and PE)	5	2329	Odds Ratio (M‐H, Fixed, 95% CI)	0.59 [0.35, 1.01]
1.1 Hip replacement	4	1296	Odds Ratio (M‐H, Fixed, 95% CI)	0.69 [0.36, 1.30]
1.2 Knee replacement	1	723	Odds Ratio (M‐H, Fixed, 95% CI)	0.78 [0.21, 2.92]
1.3 Hip or knee replacement	1	310	Odds Ratio (M‐H, Fixed, 95% CI)	0.22 [0.05, 1.06]
2 Symptomatic DVT (proximal or distal)	4	2019	Odds Ratio (M‐H, Fixed, 95% CI)	0.73 [0.39, 1.38]
2.1 Hip replacement	4	1296	Odds Ratio (M‐H, Fixed, 95% CI)	0.80 [0.41, 1.55]
2.2 Knee replacement	1	723	Odds Ratio (M‐H, Fixed, 95% CI)	0.32 [0.03, 3.12]
3 Symptomatic PE	3	1595	Odds Ratio (M‐H, Fixed, 95% CI)	0.61 [0.16, 2.33]
3.1 Hip replacement	3	872	Odds Ratio (M‐H, Fixed, 95% CI)	0.13 [0.01, 2.56]
3.2 Knee replacement	1	723	Odds Ratio (M‐H, Fixed, 95% CI)	1.47 [0.24, 8.83]
4 Total VTE (symptomatic and asymptomatic)	6	2544	Odds Ratio (M‐H, Fixed, 95% CI)	0.39 [0.28, 0.56]
4.1 Hip replacement	5	1511	Odds Ratio (M‐H, Fixed, 95% CI)	0.37 [0.25, 0.56]
4.2 Knee replacement	1	723	Odds Ratio (M‐H, Fixed, 95% CI)	0.78 [0.21, 2.92]
4.3 Hip or knee replacement	1	310	Odds Ratio (M‐H, Fixed, 95% CI)	0.38 [0.16, 0.90]
5 Asymptomatic DVT	5	1304	Odds Ratio (M‐H, Fixed, 95% CI)	0.38 [0.24, 0.60]
5.1 Hip replacement	4	994	Odds Ratio (M‐H, Fixed, 95% CI)	0.35 [0.21, 0.58]
5.2 Hip or knee replacement	1	310	Odds Ratio (M‐H, Fixed, 95% CI)	0.54 [0.19, 1.52]
6 All‐cause mortality	5	2518	Odds Ratio (M‐H, Fixed, 95% CI)	1.01 [0.31, 3.26]
6.1 Hip replacement	4	1485	Odds Ratio (M‐H, Fixed, 95% CI)	0.56 [0.11, 2.75]
6.2 Knee replacement	1	723	Odds Ratio (M‐H, Fixed, 95% CI)	0.98 [0.06, 15.65]
6.3 Hip or knee replacement	1	310	Odds Ratio (M‐H, Fixed, 95% CI)	4.69 [0.22, 98.42]
7 Adverse events	2	460	Odds Ratio (M‐H, Fixed, 95% CI)	1.06 [0.68, 1.64]
7.1 Hip replacement	2	460	Odds Ratio (M‐H, Fixed, 95% CI)	1.06 [0.68, 1.64]
8 Bleeding ‐ major	5	2500	Odds Ratio (M‐H, Fixed, 95% CI)	0.59 [0.14, 2.46]
8.1 Hip replacement	4	1494	Odds Ratio (M‐H, Fixed, 95% CI)	0.32 [0.03, 3.10]
8.2 Knee replacement	1	696	Odds Ratio (M‐H, Fixed, 95% CI)	0.99 [0.14, 7.06]
8.3 Hip or knee replacement	1	310	Odds Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
9 Bleeding ‐ minor	5	2500	Odds Ratio (M‐H, Fixed, 95% CI)	2.01 [1.43, 2.81]
9.1 Hip replacement	4	1494	Odds Ratio (M‐H, Fixed, 95% CI)	2.25 [1.53, 3.30]
9.2 Knee replacement	1	696	Odds Ratio (M‐H, Fixed, 95% CI)	1.23 [0.58, 2.59]
9.3 Hip or knee replacement	1	310	Odds Ratio (M‐H, Fixed, 95% CI)	2.79 [0.11, 69.13]
10 Reoperation	1	179	Odds Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
10.1 Hip replacement	1	179	Odds Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]