Background Patient blood management (PBM) interventions aim to improve clinical outcomes by reducing bleeding and transfusion. We assessed whether existing evidence supports the routine use of combinations of these interventions during and after major surgery. Methods Five systematic reviews and a National Institute of Health and Care Excellence health economic review of trials of common PBM interventions enrolling participants of any age undergoing surgery were updated. The last search was on June 1, 2019. Studies in trauma, burns, gastrointestinal haemorrhage, gynaecology, dentistry, or critical care were excluded. The co-primary outcomes were: risk of receiving red cell transfusion and 30-day or hospital all-cause mortality. Treatment effects were estimated using random-effects models and risk ratios (RR) with 95% confidence intervals (CIs). Heterogeneity assessments used I 2 . Network meta-analyses used a frequentist approach. The protocol was registered prospectively (PROSPERO CRD42018085730). Results Searches identified 393 eligible randomised controlled trials enrolling 54 917 participants. PBM interventions resulted in a reduction in exposure to red cell transfusion (RR=0.60; 95% CI 0.57, 0.63; I 2 =77%), but had no statistically significant treatment effect on 30-day or hospital mortality (RR=0.93; 95% CI 0.81, 1.07; I 2 =0%). Treatment effects were consistent across multiple secondary outcomes, sub-groups and sensitivity analyses that considered clinical setting, type of intervention, and trial quality. Network meta-analysis did not demonstrate additive benefits from the use of multiple interventions. No trial demonstrated that PBM was cost-effective. Conclusions In randomised trials, PBM interventions do not have important clinical benefits beyond reducing bleeding and transfusion in people undergoing major surgery.

Background The aim was to investigate whether preoperative weight loss results in improved clinical outcomes in surgical patients with clinically significant obesity. Methods This was a systematic review and aggregate data meta‐analysis of RCTs and cohort studies. PubMed, MEDLINE, Embase and CINAHL Plus databases were searched from inception to February 2018. Eligibility criteria were: studies assessing the effect of weight loss interventions (low‐energy diets with or without an exercise component) on clinical outcomes in patients undergoing any surgical procedure. Data on 30‐day or all‐cause in‐hospital mortality were extracted and synthesized in meta‐analyses. Postoperative thromboembolic complications, duration of surgery, infection and duration of hospital stay were also assessed. Results A total of 6060 patients in four RCTs and 12 cohort studies, all from European and North American centres, were identified. Most were in the field of bariatric surgery and all had some methodological limitations. The pooled effect estimate suggested that preoperative weight loss programmes were effective, leading to significant weight reduction compared with controls: mean difference –7·42 (95 per cent c.i. –10·09 to –4·74) kg (P < 0·001). Preoperative weight loss interventions were not associated with a reduction in perioperative mortality (odds ratio 1·41, 95 per cent c.i. 0·24 to 8·40; I2 = 0 per cent, P = 0·66) but the event rate was low. The weight loss groups had shorter hospital stay (by 27 per cent). No differences were found for morbidity. Conclusion This limited preoperative weight loss has advantages but may not alter the postoperative morbidity or mortality risk.