1. Results of stratified analyses on symptomatic venous thromboembolism for LMWH versus no thromboprophylaxis.
| Variable | No of trials | No of participants (LMWH) | No of participants (control) | RR (95% CI) |
Heterogeneity I2 statistic/Tau2 |
P for interaction |
| All trials | 11 | 2168 | 1763 | 0.62 (0.46 to 0.83) | 0.0/0.00 | — |
| Type of LMWH | 0.530 | |||||
| Dalteparin | 6 | 508 | 491 | 0.66 (0.40 to 1.07) | 0.0/0.00 | — |
| Certoparin | 1 | 442 | 441 | 0.57 (0.24 to 1.35) | NA | |
| Nadroparin | 1 | 769 | 381 | 0.50 (0.22 to 1.13) | NA | |
| Enoxaparin | 1 | 160 | 152 | 0.43 (0.21 to 0.88) | NA | |
| Bemiparin | 1 | 20 | 18 | 0.10 (0.01 to 1.75) | NA | |
| Tinzaparin | 1 | 269 | 280 | 0.94 (0.51 to 1.73) | NA | |
| Type of dosage | 0.965 | |||||
| Prophylactic | 8 | 1680 | 1271 | 0.62 (0.42 to 0.93) | 0.0/0.00 | — |
| Higher than prophylactic | 3 | 488 | 492 | 0.58 (0.32 to 1.05) | 44.2/0.12 | |
| Treatment duration | 0.646 | |||||
| < 12 weeks | 3 | 378 | 388 | 0.74 (0.42 to 1.31) | 8.7/0.03 | — |
| 12–24 weeks | 3 | 879 | 493 | 0.56 (0.29 to 1.11) | 0.0/0.00 | |
| > 24 weeks | 5 | 911 | 882 | 0.56 (0.37 to 0.85) | 0.0/0.00 | |
| Type of cancera | 0.683 | |||||
| Mixed | 4 | 878 | 603 | 0.74 (0.36 to 1.49) | 0.0/0.00 | — |
| Lung | 5 | 798 | 684 | 0.62 (0.38 to 1.02) | 6.9/0.03 | |
| Pancreatic | 2 | 219 | 212 | 0.41 (0.23 to 0.75) | 0.0/0.00 | |
| Glioma | 1 | 99 | 87 | 0.74 (0.35 to 1.57) | NA | |
| Breast cancer | 1 | 174 | 177 | 0.76 (0.17 to 3.36) | NA | |
| Presence of metastatic diseaseb | 0.237 | |||||
| Yes, mixed population | 5 | 519 | 508 | 0.50 (0.30 to 0.82) | 0.0/0.00 | — |
| No | 2 | 289 | 298 | 0.48 (0.07 to 3.56) | 55.4/1.38 | |
| Allocation concealment | 0.935 | |||||
| Adequate | 8 | 1634 | 1232 | 0.62 (0.45 to 0.85) | 0.0/0.00 | — |
| Inadequate or unclear | 3 | 534 | 531 | 0.60 (0.28 to 1.28) | 0.0/0.00 | |
| Blinding of participants | 0.975 | |||||
| Double‐blind | 4 | 1500 | 1093 | 0.62 (0.40 to 0.96) | 0.0/0.00 | — |
| Inadequate or unclear blinding | 7 | 668 | 670 | 0.62 (0.42 to 0.91) | 0.0/0.00 | |
| Intention‐to‐treat analysis | 0.317 | |||||
| Yes | 5 | 388 | 365 | 0.51 (0.33 to 0.81) | 0.0/0.00 | — |
| No or unclear | 6 | 1780 | 1398 | 0.71 (0.48 to 1.04) | 0.0/0.00 | |
| Selective outcome reporting | 0.655 | |||||
| Adequate | 9 | 1909 | 1524 | 0.65 (0.46 to 0.92) | 0.0/0.00 | — |
| Incomplete or unclear | 2 | 259 | 239 | 0.56 (0.33 to 0.95) | 5.6/0.01 | |
CI: confidence interval; LMWH: low‐molecular‐weight heparin; NA: not applicable, only one trial contributing to this stratum; RR: risk ratio. Analyses performed in STATA. aHaas 2012 contributed to both the breast cancer and lung cancer strata; Agnelli 2009 contributed both to the lung cancer and mixed cancer strata bStudies that did not report the selection criteria for metastatic disease were omitted from this analyses (Agnelli 2009; Haas 2012; Khorana 2017; Perry 2010).