Background - Findings of observational studies investigating the impact of transfusions are at odds with those of randomised controlled trials, raising concern that observational studies may be inappropriate to inform transfusion decisions. We examined whether observational data could replicate evidence from randomised controlled trials on restrictive transfusion in cardiac and orthopaedic surgery, and be generalised to broader specialties as well as to a lower haemoglobin transfusion threshold (7 g/dL).
Material and methods - A multicentre, prospective cohort study was performed at three representative regional hospitals in China between 2015 and 2016. Participants were surgical inpatients (≥18 years; hospital stay ≥24 h) in six specialties: cardiac, cerebral, vascular (CCV), and orthopaedic, general, thoracic (non-CCV). Patients with a stable haemoglobin (7-10 g/dL) constituted the primary analytic sample, while patients with ≥500 mL intra-operative bleeding were analysed separately to avoid haemoglobin instability. The association of transfusion with surgical outcomes (death, in-hospital complications) was evaluated.
Results - The transfusion rate was 10.7% in 36,607 patients (mean age, 52.5±14.3 years; 52.3% female). After restriction, stratification, and propensity score matching to reduce patients’ heterogeneity, transfusion was unrelated to death (CCV: odds ratio [OR]=0.74, 95% confidence interval [CI]: 0.16-3.39; non-CCV: OR 0.83, 95% CI: 0.36-1.94) and the composite complication (CCV: OR 1.31, 95% CI: 0.63-2.72; non-CCV: OR=1.24, 95% CI: 0.81-1.90). The results were consistent in subgroups (elderly, coronary heart disease, malignant tumour, severe illness) and applicable to patients with significant bleeding after restoration of a stable haemoglobin.
Discussion - Transfusion at a stable haemoglobin concentration of 7-10 g/dL did not alter surgical outcomes. Our results show the feasibility of observational data to expand restrictive transfusion to broader specialties and a lower transfusion threshold in surgical practice.
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