Bleeding impacting mortality after noncardiac surgery: a protocol to establish diagnostic criteria, estimate prognostic importance, and develop and validate a prediction guide in an international prospective cohort study

Timing of Major Postoperative Bleeding Among Patients Undergoing Surgery

Importance

Although major bleeding is among the most common and prognostically important perioperative complications, the relative timing of bleeding events is not well established. This information is critical for preventing bleeding complications and for informing the timing of pharmacologic thromboprophylaxis.

Objective

To determine the timing of postoperative bleeding among patients undergoing surgery for up to 30 days after surgery.

Design, Setting, and Participants

This is a secondary analysis of a prospective cohort study. Patients aged 45 years or older who underwent inpatient noncardiac surgery were recruited in 14 countries between 2007 and 2013, with follow-up until December 2014. Data analysis was performed from June to July 2023.

Exposure

Noncardiac surgery requiring overnight hospital admission.

Main Outcomes and Measures

The primary outcome (postoperative major bleeding) was a composite of the timing of the following bleeding outcomes: (1) bleeding leading to transfusion, (2) bleeding leading to a postoperative hemoglobin level less than 7 g/dL, (3) bleeding leading to death, and (4) bleeding associated with reintervention. Each of the components of the composite primary outcome (1-4) and bleeding independently associated with mortality after noncardiac surgery, which was defined as a composite of outcomes 1 to 3, were secondary outcomes.

Results

Among 39 813 patients (median [IQR] age, 63.0 [54.8-72.5] years; 19 793 women [49.7%]), there were 5340 major bleeding events (primary outcome) in 4638 patients (11.6%) within the first 30 days after surgery. Of these events, 42.7% (95% CI, 40.9%-44.6%) occurred within 24 hours after surgery, 77.7% (95% CI, 75.8%-79.5%) by postoperative day 7, 88.3% (95% CI, 86.5%-90.2%) by postoperative day 14, and 94.6% (95% CI, 92.7%-96.5%) by postoperative day 21. Within 48 hours of surgery, 56.2% of major bleeding events, 56.2% of bleeding leading to transfusion, 56.1% of bleeding independently associated with mortality after noncardiac surgery, 51.8% of bleeding associated with hemoglobin less than 7 g/dL, and 51.8% of bleeding associated with reintervention had occurred.

Conclusions and Relevance

In this cohort study, of the major postoperative bleeding events in the first 30 days, more than three-quarters occurred during the first postoperative week. These findings are useful for researchers for the planning future clinical research and for clinicians in prevention of bleeding-related surgical complications and in decision-making regarding starting of pharmacologic thromboprophylaxis after surgery.

Systematic reviews of observational studies of Risk of Thrombosis and Bleeding in General and Gynecologic Surgery (ROTBIGGS): introduction and methodology

BACKGROUND

Venous thromboembolism (VTE) and bleeding are serious and potentially fatal complications of surgical procedures. Pharmacological thromboprophylaxis decreases the risk of VTE but increases the risk of major post-operative bleeding. The decision to use pharmacologic prophylaxis therefore represents a trade-off that critically depends on the incidence of VTE and bleeding in the absence of prophylaxis. These baseline risks vary widely between procedures, but their magnitude is uncertain. Systematic reviews addressing baseline risks are scarce, needed, and require innovations in methodology. Indeed, systematic summaries of these baseline risk estimates exist neither in general nor gynecologic surgery. We will fill this knowledge gap by performing a series of systematic reviews and meta-analyses of the procedure-specific and patient risk factor stratified risk estimates in general and gynecologic surgeries.

METHODS

We will perform comprehensive literature searches for observational studies in general and gynecologic surgery reporting symptomatic VTE or bleeding estimates. Pairs of methodologically trained reviewers will independently assess the studies for eligibility, evaluate the risk of bias by using an instrument developed for this review, and extract data. We will perform meta-analyses and modeling studies to adjust the reported risk estimates for the use of thromboprophylaxis and length of follow up. We will derive the estimates of risk from the median estimates of studies rated at the lowest risk of bias. The primary outcomes are the risk estimates of symptomatic VTE and major bleeding at 4 weeks post-operatively for each procedure stratified by patient risk factors. We will apply the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate evidence certainty.

DISCUSSION

This series of systematic reviews, modeling studies, and meta-analyses will inform clinicians and patients regarding the trade-off between VTE prevention and bleeding in general and gynecologic surgeries. Our work advances the standards in systematic reviews of surgical complications, including assessment of risk of bias, criteria for arriving at the best estimates of risk (including modeling of the timing of events and dealing with suboptimal data reporting), dealing with subgroups at higher and lower risk of bias, and use of the GRADE approach.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021234119.

Association Between Perioperative Atrial Fibrillation and Long-term Risks of Stroke and Death in Noncardiac Surgery: Systematic Review and Meta-analysis

BACKGROUND

Atrial fibrillation (AF) is frequently reported as a complication of noncardiac surgery. It is unknown whether new-onset perioperative AF is associated with an increased risk of stroke and death beyond the perioperative period. We performed a systematic review and meta-analysis to assess the long-term risks of stroke and mortality associated with new-onset perioperative AF after noncardiac surgery.

METHODS

MEDLINE and EMBASE were searched from inception to March 2020 for studies reporting on the association between perioperative AF and the risk of stroke and death occurring beyond 30 days after noncardiac surgery. Reference screening, study selection, data extraction, and quality assessment were performed in duplicate. Data were pooled using inverse variance-weighted random-effects models and presented as risk ratios (RRs).

RESULTS

From 7344 citations, we included 31 studies (3,529,493 patients). The weighted mean incidence of perioperative AF was 0.7%. During a mean follow-up of 28.1 ± 9.4 months, perioperative AF was associated with an increased risk of stroke (1.5 vs 0.9 strokes per 100 patient-years; RR: 2.9, 95% confidence interval [CI]: 2.1-3.9, I2 = 78%). Perioperative AF was also associated with a significantly higher risk of all-cause mortality (21.0 vs 7.6 deaths per 100 patient-years; RR: 1.8, 95% CI: 1.5-2.2, I2 = 94%). The pooled adjusted hazard ratios for stroke and all-cause mortality were 1.9 (95% CI: 1.6-2.2, I2 = 31%) and 1.5 (95% CI: 1.3-1.7, I2 = 20%), respectively.

CONCLUSIONS

Patients who had perioperative AF after noncardiac surgery had a higher long-term risk of stroke and mortality compared with patients who did not. Whether this risk is modifiable with oral anticoagulation therapy should be investigated.

The Attributable Mortality of Postoperative Bleeding Exceeds the Attributable Mortality of Postoperative Venous Thromboembolism

BACKGROUND

Bleeding and venous thromboembolic disease are considered important sources of postoperative morbidity and mortality. Clinically, treatment of these 2 disorders is often competing. We sought to better understand the relative contributions of bleeding and venous thromboembolic disease to postoperative attributable mortality in a national cohort.

METHODS

A retrospective analysis of the 2006-2017 American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database was performed to assess the adjusted odds ratio and attributable mortality for postoperative bleeding and venous thromboembolism, adjusted by year.

RESULTS

After adjustment for confounding variables, bleeding exhibited a high postoperative attributable mortality in every year studied. Venous thromboembolism appeared to contribute minimal attributable mortality.

CONCLUSIONS

Bleeding complications are a consistent source of attributable mortality in surgical patients, while the contribution of venous thromboembolic disease appears to be minimal in this analysis. Further studies are warranted to better understand the etiology of this disparity.

Accountability, research transparency and data reporting

More than one published paper are often derived from analyzing the same cohort of individuals to make full use of the collected information. Preplanned study outcomes are generally mentioned in open databases while exhaustive information on methodological aspects are provided in submitted articles.

Bleeding Independently associated with Mortality after noncardiac Surgery (BIMS): an international prospective cohort study establishing diagnostic criteria and prognostic importance

BACKGROUND

We aimed to establish diagnostic criteria for bleeding independently associated with mortality after noncardiac surgery (BIMS) defined as bleeding during or within 30 days after noncardiac surgery that is independently associated with mortality within 30 days of surgery, and to estimate the proportion of 30-day postoperative mortality potentially attributable to BIMS.

METHODS

This was a prospective cohort study of participants ≥45 yr old having inpatient noncardiac surgery at 12 academic hospitals in eight countries between 2007 and 2011. Cox proportional hazards models evaluated the adjusted relationship between candidate diagnostic criteria for BIMS and all-cause mortality within 30 days of surgery.

RESULTS

Of 16 079 participants, 2.0% (315) died and 36.1% (5810) met predefined screening criteria for bleeding. Based on independent association with 30-day mortality, BIMS was identified as bleeding leading to a postoperative haemoglobin <70 g L^-1, transfusion of ≥1 unit of red blood cells, or that was judged to be the cause of death. Bleeding independently associated with mortality after noncardiac surgery occurred in 17.3% of patients (2782). Death occurred in 5.8% of patients with BIMS (161/2782), 1.3% (39/3028) who met bleeding screening criteria but not BIMS criteria, and 1.1% (115/10 269) without bleeding. BIMS was associated with mortality (adjusted hazard ratio: 1.87; 95% confidence interval: 1.42-2.47). We estimated the proportion of 30-day postoperative deaths potentially attributable to BIMS to be 20.1-31.9%.

CONCLUSIONS

Bleeding independently associated with mortality after noncardiac surgery (BIMS), defined as bleeding that leads to a postoperative haemoglobin <70 g L^-1, blood transfusion, or that is judged to be the cause of death, is common and may account for a quarter of deaths after noncardiac surgery.

CLINICAL TRIAL REGISTRATION

NCT00512109.

Preoperative prediction of Bleeding Independently associated with Mortality after noncardiac Surgery (BIMS): an international prospective cohort study

BACKGROUND

Diagnostic criteria for Bleeding Independently associated with Mortality after noncardiac Surgery (BIMS) have been defined as bleeding that leads to a postoperative haemoglobin <70 g L^-1, leads to blood transfusion, or is judged to be the direct cause of death. Preoperative prediction guides for BIMS can facilitate informed consent and planning of perioperative care.

METHODS

In a prospective cohort study of 16 079 participants aged ≥45 yr having inpatient noncardiac surgery at 12 academic hospitals in eight countries between 2007 and 2011, 17.3% (2782) experienced BIMS. An electronic risk calculator for BIMS was developed and internally validated by logistic regression with bootstrapping, and further simplified to a risk index. Decision curve analysis assessed the potential utility of each prediction guide compared with a strategy of identifying risk of BIMS based on preoperative haemoglobin <120 g L^-1.

RESULTS

With information about the type of surgery, preoperative haemoglobin, age, sex, functional status, kidney function, history of high-risk coronary artery disease, and active cancer, the risk calculator accurately predicted BIMS (bias-corrected C-statistic, 0.84; 95% confidence interval, 0.837-0.852). A simplified index based on preoperative haemoglobin <120 g L^-1, open surgery, and high-risk surgery also predicted BIMS, but less accurately (C-statistic, 0.787; 95% confidence interval, 0.779-0.796). Both prediction guides could improve decision making compared with knowledge of haemoglobin <120 g L^-1 alone.

CONCLUSIONS

BIMS, defined as bleeding that leads to a postoperative haemoglobin <70 g L^-1, leads to blood transfusion, or that is judged to be the direct cause of death, can be predicted by a simple risk index before surgery.

CLINICAL TRIAL REGISTRATION

NCT00512109.