Inflammation as a Predictor of Abdominal Aortic Aneurysm Growth and Rupture: A Systematic Review of Imaging Biomarkers

BACKGROUND

Methods are required to identify abdominal aortic aneurysms (AAAs) at increased risk of rupture. Inflammatory characteristics of AAA can be visualised using advanced imaging techniques and have been proposed as potential predictors of aneurysm progression. The objective of this review was to determine which inflammatory imaging biomarkers are associated with AAA growth and rupture.

METHODS

A systematic review was carried out in accordance with the PRISMA guidelines. The electronic databases of Medline (PubMed), Embase, and the Cochrane Library were searched up to January 1, 2016 for studies to determine the potential association between inflammatory imaging biomarkers and AAA growth or rupture.

RESULTS

Seven studies were included, comprising 202 AAA patients. (18)F-fluoro-deoxy-glucose positron emission tomography ((18)F-FDG PET-CT) was evaluated in six studies. Magnetic resonance imaging with ultrasmall superparamagnetic particles of iron oxide (USPIO-MRI) was evaluated in one study. Two of six (18)F-FDG PET-CT studies reported a significant negative correlation (r=.383, p = .015) or a significant negative association (p = .04). Four of six (18)F-FDG PET-CT studies reported no significant association between (18)F-FDG uptake and AAA growth. The single study investigating USPIO-MRI demonstrated that AAA growth was three times higher in patients with focal USPIO uptake in the AAA wall compared to patients with diffuse or no USPIO uptake in the wall (0.66 vs. 0.24 vs. 0.22 cm/y, p = .020). In the single study relating (18)F-FDG uptake results to AAA rupture, the association was not significant.

CONCLUSIONS

Current evidence shows contradictory associations between (18)F-FDG uptake and AAA growth. Data on the association with rupture are insufficient. Based on the currently available evidence, neither (18)F-FDG PET-CT nor USPIO-MRI can be implemented as growth or rupture prediction tools in daily practice. The heterogeneous results reflect the complex and partially unclear relationship between inflammatory processes and AAA progression.

Biomechanical Imaging Markers as Predictors of Abdominal Aortic Aneurysm Growth or Rupture: A Systematic Review

OBJECTIVES

Biomechanical characteristics, such as wall stress, are important in the pathogenesis of abdominal aortic aneurysms (AAA) and can be visualised and quantified using imaging techniques. This systematic review aims to present an overview of all biomechanical imaging markers that have been studied in relation to AAA growth and rupture.

METHODS

This systematic review followed the PRISMA guidelines. A search in Medline, Embase, and the Cochrane Library identified 1503 potentially relevant articles. Studies were included if they assessed biomechanical imaging markers and their potential association with growth or rupture.

RESULTS

Twenty-seven articles comprising 1730 patients met the inclusion criteria. Eighteen studies performed wall stress analysis using finite element analysis (FEA), 13 of which used peak wall stress (PWS) to quantify wall stress. Ten of 13 case control FEA studies reported a significantly higher PWS for symptomatic or ruptured AAAs than for intact AAAs. However, in some studies there was confounding bias because of baseline differences in aneurysm diameter between groups. Clinical heterogeneity in methodology obstructed a meaningful meta-analysis of PWS. Three of five FEA studies reported a significant positive association between several wall stress markers, such as PWS and 99th percentile stress, and growth. One study reported a significant negative association and one other study reported no significant association. Studies assessing wall compliance, the augmentation index and wall stress analysis using Laplace's law, computational fluid dynamics and fluid structure interaction were also included in this systematic review.

CONCLUSIONS

Although PWS is significantly higher in symptomatic or ruptured AAAs in most FEA studies, confounding bias, clinical heterogeneity, and lack of standardisation limit the interpretation and generalisability of the results. Also, there is conflicting evidence on whether increased wall stress is associated with growth.

Efficacy of different preoperative skin antiseptics on the incidence of surgical site infections: a systematic review, GRADE assessment, and network meta-analysis

BACKGROUND

Surgical site infection (SSI) is the most common postoperative complication and substantially increases health-care costs. Published meta-analyses and international guidelines differ with regard to which preoperative skin antiseptic solution and concentration has the highest efficacy. We aimed to compare the efficacy of different skin preparation solutions and concentrations for the prevention of SSIs, and to provide an overview of current guidelines.

METHODS

This systematic review and network meta-analysis compared different preoperative skin antiseptics in the prevention of SSIs in adult patients undergoing surgery of any wound classification. We searched for randomised controlled trials (RCTs) in MEDLINE, Embase, and Cochrane CENTRAL, published up to Nov 23, 2021, that directly compared two or more antiseptic agents (ie, chlorhexidine, iodine, or olanexidine) or concentrations in aqueous and alcohol-based solutions. We excluded paediatric, animal, and non-randomised studies, and studies not providing standard preoperative intravenous antibiotic prophylaxis. Studies with no SSIs in both groups were excluded from the quantitative analysis. Two reviewers screened and reviewed eligible full texts and extracted data. The primary outcome was the occurrence of SSI (ie, superficial, deep, and organ space). We conducted a frequentist random effects network meta-analysis to estimate the network effects of the skin preparation solutions on the prevention of SSIs. A risk-of-bias and Grading of Recommendations, Assessment, Development, and Evaluation assessment were done to determine the certainty of the evidence. This study is registered with PROSPERO, CRD42021293554.

FINDINGS

Overall, 2326 articles were identified, 33 studies were eligible for the systematic review, and 27 studies with 17 735 patients reporting 2144 SSIs (overall incidence of 12·1%) were included in the quantitative analysis. Only 2·0-2·5% chlorhexidine in alcohol (relative risk 0·75, 95% CI 0·61-0·92) and 1·5% olanexidine (0·49, 0·26-0·92) significantly reduced the rate of SSIs compared with aqueous iodine. For clean surgery, we found no difference in efficacy between different concentrations of chlorhexidine in alcohol. Seven RCTs were at high risk of bias, 24 had some concerns, and two had low risk of bias. Heterogeneity across the studies was moderate (I²=27·5%), and netsplitting did not show inconsistencies between direct and indirect comparisons. Five of ten studies that mentioned adverse events related to the skin preparation solutions reported no adverse events, and five reported a total of 56 mild events (mainly erythema, pruritus, dermatitis, skin irritation, or mild allergic symptoms); none reported a substantial difference in adverse events between groups.

INTERPRETATION

For adult patients undergoing a surgical procedure of any wound classification, skin preparation using either 2·0-2·5% chlorhexidine in alcohol or 1·5% olanexidine is most effective in the prevention of SSIs. For clean surgery, no specific concentration of chlorhexidine in alcohol can be recommended. The efficacy of olanexidine was established by a single randomised trial and further investigation is needed.

FUNDING

Dutch Association for Quality Funds Medical Specialists.

Incisional negative pressure wound therapy for the prevention of surgical site infection: an up-to-date meta-analysis and trial sequential analysis

Background

The evidence on prophylactic use of negative pressure wound therapy on primary closed incisional wounds (iNPWT) for the prevention of surgical site infections (SSI) is confusing and ambiguous. Implementation in daily practice is impaired by inconsistent recommendations in current international guidelines and published meta-analyses. More recently, multiple new randomised controlled trials (RCTs) have been published. We aimed to provide an overview of all meta-analyses and their characteristics; to conduct a new and up-to-date systematic review and meta-analysis and Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessment; and to explore the additive value of new RCTs with a trial sequential analysis (TSA).

Methods

PubMed, Embase and Cochrane CENTRAL databases were searched from database inception to October 24, 2022. We identified existing meta-analyses covering all surgical specialties and RCTs studying the effect of iNPWT compared with standard dressings in all types of surgery on the incidence of SSI, wound dehiscence, reoperation, seroma, hematoma, mortality, readmission rate, skin blistering, skin necrosis, pain, and adverse effects of the intervention. We calculated relative risks (RR) with corresponding 95% confidence intervals (CI) using a Mantel-Haenszel random-effects model. We assessed publication bias with a comparison-adjusted funnel plot. TSA was used to assess the risk of random error. The certainty of evidence was evaluated using the Cochrane Risk of Bias-2 (RoB2) tool and GRADE approach. This study is registered with PROSPERO, CRD42022312995.

Findings

We identified eight previously published general meta-analyses investigating iNPWT and compared their results to present meta-analysis. For the updated systematic review, 57 RCTs with 13,744 patients were included in the quantitative analysis for SSI, yielding a RR of 0.67 (95% CI: 0.59-0.76, I2 = 21%) for iNPWT compared with standard dressing. Certainty of evidence was high. Compared with previous meta-analyses, the RR stabilised, and the confidence interval narrowed. In the TSA, the cumulative Z-curve crossed the trial sequential monitoring boundary for benefit, confirming the robustness of the summary effect estimate from the meta-analysis.

Interpretation

In this up-to-date meta-analysis, GRADE assessment shows high-certainty evidence that iNPWT is effective in reducing SSI, and uncertainty is less than in previous meta-analyses. TSA indicated that further trials are unlikely to change the effect estimate for the outcome SSI; therefore, if future research is to be conducted on iNPWT, it is crucial to consider what the findings will contribute to the existing robust evidence.

Funding

Dutch Association for Quality Funds Medical Specialists.

Triclosan-Containing Sutures for the Prevention of Surgical Site Infection: A Systematic Review and Meta-Analysis

Importance

International guidelines recommend the use of triclosan-containing sutures for the prevention of surgical site infections. However, controversy still remains about triclosan-containing suture use in clinical practice since several new randomized clinical trials (RCTs) have shown contradicting results.

Objective

To update a previous systematic review and meta-analysis of the association of triclosan-containing sutures with surgical site infections and explore the potential added value of new RCTs.

Data Sources

PubMed, Embase, and Cochrane CENTRAL databases were searched from January 1, 2015, to March 14, 2023. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed.

Study Selection

Published RCTs comparing triclosan-containing sutures with similar sutures without triclosan for the prevention of surgical site infections in any type of surgery were included.

Data Extraction and Synthesis

Two authors (H.J. and A.S.T.) independently extracted and pooled data in a random-effects (Mantel-Haenszel) model. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation approach, and trial sequential analysis was used to estimate whether further studies would reveal different outcomes.

Main Outcomes and Measures

The primary outcome was the incidence of surgical site infections, expressed as relative risk (RRs) and corresponding 95% CIs. Secondary outcomes were the incidence of surgical site infections according to depth (superficial incisional, deep incisional, and organ/space) and adverse events related to triclosan-containing sutures.

Results

The systematic review yielded 15 additional RCTs compared with a previous published review in 2017. A meta-analysis of 31 studies including 17 968 participants (62% male) undergoing various types of surgery was performed. Use of triclosan-containing sutures was associated with fewer surgical site infections compared with sutures without triclosan (RR, 0.75; 95% CI, 0.65-0.86). The certainty of evidence was moderate after downgrading for heterogeneity (τ2 = 0.04; I2 = 43%). In the trial sequential analysis of all trials and a sensitivity analysis excluding studies with a high risk of bias, the cumulative z curve crossed the trial sequential monitoring boundary for benefit, confirming the robustness of the summary effect estimate.

Conclusions and Relevance

This updated meta-analysis found moderate-certainty evidence that wound closure with triclosan-containing sutures was associated with a lower risk of surgical site infections. The trial sequential analysis suggests that future trials that would change these findings are improbable.

Systematic review and meta-analysis of goal-directed haemodynamic therapy algorithms during surgery for the prevention of surgical site infection

Background

Surgical site infection (SSI) is the most common postoperative complication. Goal-directed haemodynamic therapy (GDHT) may help to prevent SSI, but recommendations for its use initially have been set at conditional because of low-certainty evidence at the time. An updated systematic review with SSI as the primary endpoint has not been performed since 2011, and important new evidence has emerged. We assessed the influence of GDHT on SSI and other postoperative outcomes.

Methods

We searched Ovid/MEDLINE, Excerpta Medica Database (Embase.com), and Cochrane library from inception up to September 2024 for randomised controlled trials comparing the effect of any GDHT algorithm to conventional fluid therapy on SSI incidence in adult patients undergoing surgery and analysed eligible data using random effects. We conducted several subgroup analyses, including the risk of bias (RoB), and a trial sequential analysis (TSA). We evaluated the certainty of evidence using Grading of Recommendations, Assessment, Development, and Evaluations. This study is registered with PROSPERO, CRD42022277535.

Findings

We found 75 studies that met the inclusion criteria with an incidence of 1,478 SSI among 13,010 patients (11.4%). The incidence of SSI was reduced from 13.3% in the conventional fluid therapy to 9.4% after GDHT (absolute risk reduction 3.9%); pooled relative risk 0.71 (95% CI 0.62-0.81). Subgroup analysis for the low RoB studies revealed comparable results. Meta-regression indicated no strong evidence for individual subgroup effects. In the TSA, the cumulative z-line crossed the boundary for effect.

Interpretation

High-certainty evidence indicates that GDHT reduces the risk of SSI when compared to conventional fluid therapy in adults undergoing surgery. New studies are unlikely to change this outcome. These findings justify a stronger recommendation for the use of GDHT.

Funding

Dutch Association for Quality Funds Medical Specialists.

A Network Meta-Analysis and GRADE Assessment of the Effect of Preoperative Oral Antibiotics with and Without Mechanical Bowel Preparation on Surgical Site Infection Rate in Colorectal Surgery

Objective

To compare the effect of different methods of bowel preparation on the incidence of surgical site infections (SSI), anastomotic leakage (AL), and mortality in patients undergoing elective colorectal surgery.

Background

Recent guidelines advise mechanical bowel preparation with oral antibiotics (MBP-OA) for the prevention of SSI in colorectal surgery. Recent trials suggest oral antibiotics (OA) alone may be sufficient.

Methods

PubMed, MEDLINE, and Embase were searched from inception until 10-08-2021. We included randomized controlled trials (RCTs) comparing multiple methods of bowel preparation (mechanical bowel preparation [MBP], OA, MBP-OA, or no preparation) with regards to clinical outcomes such as incidence of SSI, AL, and mortality rates. A frequentist random-effects network meta-analysis was conducted to estimate the network effects of the different treatment options.

Results

We included 48 studies with 13,611 patients. Compared to no preparation, combined direct and indirect network estimates showed a relative risk (RR) for SSI of 0.57 (95% confidence interval [CI], 0.45-0.72) for MBP-OA, 0.68 (95% CI, 0.49-0.95) for OA, and 1.05 (95% CI, 0.87-1.26) for MBP. The RR for MBP-OA compared to OA was 0.84 (95% CI, 0.60-1.19); in sensitivity analysis of mainly laparoscopic procedures this effect of MBP-OA was more profound (RR, 0.56; 95% CI, 0.31-0.99).

Conclusions

This network meta-analysis of RCTs finds that both mechanical bowel preparation with oral antibiotics and oral antibiotics alone are comparably effective in the prevention of SSI. The evidence is uncertain about the relative benefit of MBP-OA compared to OA alone. Therefore, it seems justified to use either of the 2 for the prevention of SSI in colorectal surgery.

Incisional Wound Irrigation for the Prevention of Surgical Site Infection: A Systematic Review and Network Meta-Analysis

Importance

Surgical site infections (SSIs) are common postoperative complications and associated with significant morbidity, mortality, and costs. Prophylactic intraoperative incisional wound irrigation is used to reduce the risk of SSIs, and there is great variation in the type of irrigation solutions and their use.

Objective

To compare the outcomes of different types of incisional prophylactic intraoperative incisional wound irrigation for the prevention of SSIs in all types of surgery.

Data Sources

PubMed, Embase, CENTRAL, and CINAHL databases were searched up to June 12, 2023.

Study Selection

Included in this study were randomized clinical trials (RCTs) comparing incisional prophylactic intraoperative incisional wound irrigation with no irrigation or comparing irrigation using different types of solutions, with SSI as a reported outcome. Studies investigating intracavity lavage were excluded.

Data Extraction and Synthesis

This systematic review and network meta-analysis is reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. Two reviewers independently extracted the data and assessed the risk of bias within individual RCTs using the Cochrane Risk of Bias 2 tool and the certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation framework. A frequentist network meta-analysis was conducted, and relative risks (RRs) with corresponding 95% CIs were reported.

Main Outcome and Measure

The primary study outcome was SSI.

Results

A total of 1587 articles were identified, of which 41 RCTs were included in the systematic review, with 17 188 patients reporting 1328 SSIs, resulting in an overall incidence of 7.7%. Compared with no irrigation, antiseptic solutions (RR, 0.60; 95% CI, 0.44-0.81; high level of certainty) and antibiotic solutions (RR, 0.46; 95% CI, 0.29-0.73; low level of certainty) were associated with a beneficial reduction in SSIs. Saline irrigation showed no statistically significant difference compared with no irrigation (RR, 0.83; 95% CI, 0.63-1.09; moderate level of certainty).

Conclusions and Relevance

This systematic review and network meta-analysis found high-certainty evidence that prophylactic intraoperative incisional wound irrigation with antiseptic solutions was associated with a reduction in SSIs. It is suggested that the use of antibiotic wound irrigation be avoided due to the inferior certainty of evidence for its outcome and global antimicrobial resistance concerns.