Summary of findings for the main comparison. Liberal versus restrictive threshold transfusion for people undergoing hip fracture surgery.
| Liberal versus restrictive threshold transfusion for people undergoing hip fracture surgery | ||||||
|
Patient or population: people undergoing hip fracture surgery1
Settings: hospital
Intervention: liberal threshold red blood cell transfusion2 Comparison: restrictive threshold red blood cell transfusion3 | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Restrictive threshold | Liberal threshold | |||||
| 30‐day mortality Follow‐up: mean 30 days | 50 per 10004 | 46 per 1000 (33 to 63) | RR 0.92 (0.67 to 1.26) | 2683 (5 studies) | ⊕⊕⊝⊝ low5,6 | ‐ |
| Inability to walk 10 feet (3 m; or across a room) without human assistance Follow‐up: mean 60 days | 283 per 10004 | 283 per 1000 (246 to 326) | RR 1.00 (0.87 to 1.15) | 2083 (2 studies) | ⊕⊕⊝⊝ low7,8 | ‐ |
| Thromboembolism (in hospital) | 20 per 10004 | 23 per 1000 (11 to 47) | RR 1.15 (0.56 to 2.37) | 2416 (4 studies) | ⊕⊕⊝⊝ low6,9 | ‐ |
| Stroke (in hospital) | 2 per 10004 | 5 per 1000 (2 to 14) | RR 2.4 (0.85 to 6.79) | 2416 (4 studies) | ⊕⊕⊝⊝ low6,9 | ‐ |
| Wound infection (in hospital) | 8 per 10004 | 13 per 1000 (6 to 27) | RR 1.61 (0.77 to 3.35) | 2332 (3 studies) | ⊕⊕⊝⊝ low6,10 | ‐ |
| Cardiovascular events ‐ myocardial infarction | 24 per 10004 | 14 per 1000 (9 to 23) | RR 0.59 (0.36 to 0.96) | 2217 (3 studies) | ⊕⊝⊝⊝ very low6,11 | ‐ |
| Respiratory infections (namely pneumonia) | 18 per 10004 | 24 per 1000 (17 to 35) | RR 1.35 (0.95 to 1.92) | 2416 (4 studies) | ⊕⊕⊝⊝ low6,12 | ‐ |
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (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; RR: risk ratio. | ||||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
1. Although we included evidence for pre‐operative, peri‐operative and postoperative transfusion, the majority of the evidence applied to postoperative transfusion.
2. The liberal transfusion threshold was a haemoglobin concentration of about 10 g/dL in four trials, and 11.3 g/dL in one trial.
3. The restrictive transfusion threshold in four trials was a haemoglobin concentration of about 8 g/dL or symptoms of anaemia, and 9.7 g/dL in one trial.
4. The assumed risk was the median control risk across studies.
5. We downgraded the evidence one level because of risk of bias: 57% of the weighting for this outcome came from one trial in which there was a statistical difference (P value = 0.003) in the number of major protocol violations post randomisation between the two transfusion threshold groups.
6. We downgraded the evidence one level because of imprecision: generally because of the small number of events in the studies reporting data for this outcome has resulted in wide confidence intervals for these studies.
7. We downgraded the evidence one level because of risk of bias: 96% of the weighting for this outcome came from one trial in which there was a statistical difference (P value = 0.003) in the number of major protocol violations post randomisation between the two transfusion threshold groups.
8. We further downgraded the evidence one level because of risk of bias: both participants and study personnel "were aware of study group assignment after randomisation" in the two studies reporting data for this subjective outcome. Given that the participants themselves are involved in assessing this outcome, knowledge of treatment allocation may influence outcome measurement.
9. We downgraded the evidence one level because of risk of bias: 60% of the weighting for this outcome came from one trial in which there was a statistical difference (P value = 0.003) in the number of major protocol violations post randomisation between the two transfusion threshold groups.
10. We downgraded the evidence one level because of risk of bias: 70% of the weighting for this outcome came from one trial in which there was a statistical difference (P value = 0.003) in the number of major protocol violations post randomisation between the two transfusion threshold groups.
11. We downgraded the evidence two levels because of risk of bias: 94% of the weighting for this outcome came from one trial in which there was a statistical difference (P value = 0.003) in the number of major protocol violations post randomisation between the two transfusion threshold groups; and, although numbers were comparable between the two transfusion threshold groups in this trial, overall 265 (13%) participants had incomplete electrocardiographic results and in 355 (18%) participants there was no blood sample for troponin testing. Thus, attrition bias was a potential problem.
12. We downgraded the evidence one level because of bias: 93% of the weighting for this outcome came from one trial in which there was a statistical difference (P value = 0.003) in the number of major protocol violations post randomisation between the two transfusion threshold groups.