Liberal versus restrictive red blood cell transfusion thresholds in acute acquired brain injury: a systematic review and meta-analysis
Bibliographic record
Abstract
Objective To evaluate the effects of liberal transfusion strategy (trigger haemoglobin ≤90–100 g/L) compared with a restrictive strategy (trigger haemoglobin ≤70–80 g/L) on long-term neurological functional outcome in anaemic adult patients with acute acquired brain injury (ABI). Design Systematic review and study-level meta-analysis of randomised controlled trials (RCTs). Data sources MEDLINE, EMBASE, Cochrane from inception to 6 February 2025. Study selection RCTs enrolling patients with acute ABI and anaemia (haemoglobin ≤100 g/L), comparing a liberal vs restrictive transfusion strategy. Data extraction and synthesis Two reviewers independently identified eligible studies, extracted data and assessed risk of bias. We performed random-effects meta-analysis of RCTs and applied Grading of Recommendations, Assessment, Development and Evaluation methodology to assess the certainty of evidence. Our primary outcome was an unfavourable neurological functional outcome, using the Glasgow Outcome or modified Rankin scales. Results Five trials enrolling 2364 patients with acute ABI and anaemia were included in the primary analysis. Liberal transfusion reduces the risk of unfavourable neurological outcome (risk ratio (RR)=0.89, 95% CI 0.84 to 0.95, high certainty). Liberal transfusion may reduce severe disability (RR=0.82, 95% CI 0.66 to 1.02, moderate certainty), and increase good recovery compared with restrictive transfusion (RR=1.29, 95% CI 0.95 to 1.76, low certainty). We found no difference in the risk of most adverse events, including death. Statistical heterogeneity was low (I 2 =0%–36%) for neurological outcomes. Conclusions In adults with acute ABI and anaemia, liberal transfusion reduces the risk of unfavourable outcome (high certainty) and possibly improves the chances of good recovery (low certainty) when compared with restrictive transfusion. PROSPERO registration number CRD42025628732.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.014 | 0.036 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.027 | 0.037 |
| Bibliometrics | 0.006 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".