Summary of findings 3. Heparin started before compared to after the surgical procedure for preventing venous thromboembolism in people undergoing bariatric surgery.
| Heparin started before versus after the surgical procedure for preventing venous thromboembolism in people undergoing bariatric surgery | |||||
| Patient or population: people undergoing bariatric surgery Setting: hospital Intervention: heparin started 12 hours before surgery Comparison: heparin started after surgery | |||||
| Outcomes | № of participants (studies) | Certainty of the evidence (GRADE) | Relative effect (95% CI) | Anticipated absolute effects* (95% CI) | |
| Risk with heparin after surgery | Risk with heparin 12 h before surgery | ||||
| VTE Follow‐up: 15 days | 100 (1 RCT) | ⊕⊕⊝⊝ Lowa,b | RR 0.11 (0.01 to 2.01) | Study population | |
| 80 per 1000 | 9 per 1000 (1 to 161) | ||||
| Major bleeding Follow‐up: 15 days | 100 (1 RCT) | ⊕⊝⊝⊝ Very lowa,d | RR 3.00 (0.13 to 71.92) | Study population | |
| 0 per 1000 | 0 per 1000 (0 to 0) |
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| All‐cause mortality Follow‐up: 15 days | 100 (1 RCT) | ⊕⊝⊝⊝ Very lowa,c | Not estimable | 1 study reported no events. | |
| VTE‐related mortality Follow‐up: 15 days | 100 (1 RCT) | ⊕⊝⊝⊝ Very lowa,c | Not estimable | 1 study reported no events. | |
| PE | Not reported | ||||
| DVT Follow‐up: 15 days | 100 (1 RCT) | ⊕⊕⊝⊝ Lowa,b | RR 0.11 (0.01 to 2.01) | Study population | |
| 80 per 1000 | 9 per 1000 (1 to 161) | ||||
| Adverse events (thrombocytopenia) | Not reported | ||||
| *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; DVT: deep vein thrombosis; PE: pulmonary embolism; RCT: randomised controlled trial; RR: risk ratio; VTE: venous thromboembolism. | |||||
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GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: 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 certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect. | |||||
aDowngraded one level due to high risk of performance bias. bDowngraded one level due to imprecision: few participants, and 95% CI consistent with possible benefit and possible harm. cDowngraded two levels due to imprecision: no events. dDowngraded two levels due to imprecision: very large CI of the absolute difference and few events.