Summary of findings for the main comparison. Low molecular weight heparin compared to no prophylaxis or placebo in prevention of venous thromboembolism in patients with lower‐limb immobilization.
| Low molecular weight heparin compared to no prophylaxis or placebo in prevention of venous thromboembolism in patients with lower‐limb immobilization | ||||||
| Patient or population: prevention of venous thromboembolism in patients with lower‐limb immobilization Setting: ambulatory setting Intervention: low molecular weight heparin Comparison: no prophylaxis or placebo | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Risk with no prophylaxis or placebo | Risk with low molecular weight heparin | |||||
| Deep venous thrombosis | Study population | OR 0.45 (0.33 to 0.61) | 1676 (7 RCTs) | ⊕⊕⊕⊝ MODERATE 1 | ||
| 174 per 1000 | 87 per 1000 (65 to 114) | |||||
| Pulmonary embolism | Study population | OR 0.50 (0.17 to 1.47) | 2517 (5 RCTs) | ⊕⊕⊝⊝ LOW 2 | ||
| 7 per 1000 | 4 per 1000 (1 to 10) | |||||
| Symptomatic venous thromboembolism | Study population | OR 0.40 (0.21 to 0.76) | 2924 (6 RCTs) | ⊕⊕⊝⊝ LOW 3 | ||
| 21 per 1000 | 9 per 1000 (5 to 16) | |||||
| Mortality due to pulmonary embolism | Study population | ‐ | 3111 (8 RCTs) | ‐ | No mortality due to pulmonary embolism was reported | |
| see comment | see comment | |||||
| Mortality due to other causes | Study population | OR 0.33 (0.01 to 8.15) |
3111 (8 RCTs) | ⊕⊕⊝⊝ LOW 4 | One death (in no prophylaxis/placebo group) was reported in the included studies | |
| 1 per 1000 | 0 per 1000 (0 to 5) |
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| Adverse outcomes | Study population | OR 2.01 (0.83 to 4.86) | 3178 (8 RCTs) | ⊕⊕⊝⊝ LOW 5 | ||
| 40 per 1000 | 78 per 1000 (34 to 170) | |||||
| *We calculated the assumed risk of the no prophylaxis or placebo group from the average risk in the no prophylaxis or placebo groups (i.e. the number of participants with events divided by total number of participants of the no prophylaxis or placebo group included in the meta‐analysis). The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; OR: odds ratio; | ||||||
| GRADE Working Group grades of evidence High quality: We are very confident that the true effect lies close to that of the estimate of the effect Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
1 Downgraded by one level as 3 out of 7 studies showed considerable risk of bias 2 Downgraded by two levels as 2 out of 5 studies showed considerable risk of bias, and imprecision of pooled results 3 Downgraded by two levels as 3 out of 6 studies showed considerable risk of bias, and imprecision of pooled results 4 Downgraded by two levels due to the low number of events, and imprecision of pooled results 5 Downgraded by two levels as 4 out of 8 studies showed considerable risk of bias, and imprecision of pooled results