Effects of interventions targeting the systemic inflammatory response to cardiac surgery on clinical outcomes in adults.

BACKGROUND: Organ injury is a common and severe complication of cardiac surgery that contributes to the majority of deaths. There are no effective treatment or prevention strategies. It has been suggested that innate immune system activation may have a causal role in organ injury. A wide range of organ protection interventions targeting the innate immune response have been evaluated in randomised controlled trials (RCTs) in adult cardiac surgery patients, with inconsistent results in terms of effectiveness. OBJECTIVES: The aim of the review was to summarise the results of RCTs of organ protection interventions targeting the innate immune response in adult cardiac surgery. The review considered whether the interventions had a treatment effect on inflammation, important clinical outcomes, or both. SEARCH METHODS: CENTRAL, MEDLINE, Embase, conference proceedings and two trial registers were searched on October 2022 together with reference checking to identify additional studies. SELECTION CRITERIA: RCTs comparing organ protection interventions targeting the innate immune response versus placebo or no treatment in adult patients undergoing cardiac surgery where the treatment effect on innate immune activation and on clinical outcomes of interest were reported. DATA COLLECTION AND ANALYSIS: Searches, study selection, quality assessment, and data extractions were performed independently by pairs of authors. The primary inflammation outcomes were peak IL-6 and IL-8 concentrations in blood post-surgery. The primary clinical outcome was in-hospital or 30-day mortality. Treatment effects were expressed as risk ratios (RR) and standardised mean difference (SMD) with 95% confidence intervals (CI). Meta-analyses were performed using random effects models, and heterogeneity was assessed using I2. MAIN RESULTS: A total of 40,255 participants from 328 RCTs were included in the synthesis. The effects of treatments on IL-6 (SMD -0.77, 95% CI -0.97 to -0.58, I2 = 92%) and IL-8 (SMD -0.92, 95% CI -1.20 to -0.65, I2 = 91%) were unclear due to heterogeneity. Heterogeneity for inflammation outcomes persisted across multiple sensitivity and moderator analyses. The pooled treatment effect for in-hospital or 30-day mortality was RR 0.78, 95% CI 0.68 to 0.91, I2 = 0%, suggesting a significant clinical benefit. There was little or no treatment effect on mortality when analyses were restricted to studies at low risk of bias. Post hoc analyses failed to demonstrate consistent treatment effects on inflammation and clinical outcomes. Levels of certainty for pooled treatment effects on the primary outcomes were very low. AUTHORS' CONCLUSIONS: A systematic review of RCTs of organ protection interventions targeting innate immune system activation did not resolve uncertainty as to the effectiveness of these treatments, or the role of innate immunity in organ injury following cardiac surgery.

Activation of the innate immune response and organ injury after cardiac surgery: a systematic review and meta-analysis of randomised trials and analysis of individual patient data from randomised and non-randomised studies.

BACKGROUND: It is unclear whether the innate immune response represents a therapeutic target for organ protection strategies in cardiac surgery. METHODS: A systematic review of trials of interventions targeting the inflammatory response to cardiac surgery reporting treatment effects on both innate immune system cytokines and organ injury was performed. The protocol was registered at the International Prospective Register of Systematic Reviews: CRD42020187239. Searches of the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase were performed. Random-effects meta-analyses were used for the primary analysis. A separate analysis of individual patient data from six studies (n=785) explored sources of heterogeneity for treatment effects on cytokine levels. RESULTS: Searches to May 2020 identified 251 trials evaluating 24 interventions with 20 582 participants for inclusion. Most trials had important limitations. Methodological limitations of the included trials and heterogeneity of the treatment effects on cytokine levels between trials limited interpretation. The primary analysis demonstrated inconsistency in the direction of the treatment effects on innate immunity and organ failure or death between interventions. Analyses restricted to important subgroups or trials with fewer limitations showed similar results. Meta-regression, pooling available data from all trials, demonstrated no association between the direction of the treatment effects on inflammatory cytokines and organ injury or death. The analysis of individual patient data demonstrated heterogeneity in the association between the cytokine response and organ injury after cardiac surgery for people >75 yr old and those with some chronic diseases. CONCLUSIONS: The certainty of the evidence for a causal relationship between innate immune system activation and organ injury after cardiac surgery is low.

Patient blood management interventions do not lead to important clinical benefits or cost-effectiveness for major surgery: a network meta-analysis.

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 I2. 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; I2=77%), but had no statistically significant treatment effect on 30-day or hospital mortality (RR=0.93; 95% CI 0.81, 1.07; I2=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.