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Health Technology Assessment... Sep 2013Small abdominal aortic aneurysms (AAAs; 3.0-5.4 cm in diameter) are usually asymptomatic and managed by regular ultrasound surveillance until they grow to a diameter... (Meta-Analysis)
Meta-Analysis Review
Systematic review and meta-analysis of the growth and rupture rates of small abdominal aortic aneurysms: implications for surveillance intervals and their cost-effectiveness.
BACKGROUND
Small abdominal aortic aneurysms (AAAs; 3.0-5.4 cm in diameter) are usually asymptomatic and managed by regular ultrasound surveillance until they grow to a diameter threshold (commonly 5.5 cm) at which surgical intervention is considered. The choice of appropriate surveillance intervals is governed by the growth and rupture rates of small AAAs, as well as their relative cost-effectiveness.
OBJECTIVES
The aim of this series of studies was to inform the evidence base for small AAA surveillance strategies. This was achieved by literature review, collation and analysis of individual patient data, a focus group and health economic modelling.
DATA SOURCES
We undertook systematic literature reviews of growth rates and rupture rates of small AAAs. The databases MEDLINE, EMBASE on OvidSP, Cochrane Central Register of Controlled Trials 2009 Issue 4, ClinicalTrials.gov, and controlled-trials.com were searched from inception up until the end of 2009. We also obtained individual data on 15,475 patients from 18 surveillance studies.
REVIEW METHODS
Systematic reviews of publications identified 15 studies providing small AAA growth rates, and 14 studies with small AAA rupture rates, up to December 2009 (later updated to September 2012). We developed statistical methods to analyse individual surveillance data, including the effects of patient characteristics, to inform the choice of surveillance intervals and provide inputs for health economic modelling. We updated an existing health economic model of AAA screening to address the cost-effectiveness of different surveillance intervals.
RESULTS
In the literature reviews, the mean growth rate was 2.3 mm/year and the reported rupture rates varied between 0 and 1.6 ruptures per 100 person-years. Growth rates increased markedly with aneurysm diameter, but insufficient detail was available to guide surveillance intervals. Based on individual surveillance data, for each 0.5-cm increase in AAA diameter, growth rates increased by about 0.5 mm/year and rupture rates doubled. To control the risk of exceeding 5.5 cm to below 10% in men, on average a 7-year surveillance interval is sufficient for a 3.0-cm aneurysm, whereas an 8-month interval is necessary for a 5.0-cm aneurysm. To control the risk of rupture to below 1%, the corresponding estimated surveillance intervals are 9 years and 17 months. Average growth rates were higher in smokers (by 0.35 mm/year) and lower in patients with diabetes (by 0.51 mm/year). Rupture rates were almost fourfold higher in women than men, doubled in current smokers and increased with higher blood pressure. Increasing the surveillance interval from 1 to 2 years for the smallest aneurysms (3.0-4.4 cm) decreased costs and led to a positive net benefit. For the larger aneurysms (4.5-5.4 cm), increasing surveillance intervals from 3 to 6 months led to equivalent cost-effectiveness.
LIMITATIONS
There were no clear reasons why the growth rates varied substantially between studies. Uniform diagnostic criteria for rupture were not available. The long-term cost-effectiveness results may be susceptible to the modelling assumptions made.
CONCLUSIONS
Surveillance intervals of several years are clinically acceptable for men with AAAs in the range 3.0-4.0 cm. Intervals of around 1 year are suitable for 4.0-4.9-cm AAAs, whereas intervals of 6 months would be acceptable for 5.0-5.4-cm AAAs. These intervals are longer than those currently employed in the UK AAA screening programmes. Lengthening surveillance intervals for the smallest aneurysms was also shown to be cost-effective. Future work should focus on optimising surveillance intervals for women, studying whether or not the threshold for surgery should depend on patient characteristics, evaluating the usefulness of surveillance for those with aortic diameters of 2.5-2.9 cm, and developing interventions that may reduce the growth or rupture rates of small AAAs.
FUNDING
The National Institute for Health Research Health Technology Assessment programme.
Topics: Aneurysm, Ruptured; Aortic Aneurysm, Abdominal; Cost-Benefit Analysis; Disease Progression; Humans; Risk Factors; Rupture, Spontaneous
PubMed: 24067626
DOI: 10.3310/hta17410 -
European Journal of Vascular and... May 2016The growth rates of thoracic aortic aneurysms (TAAs) and factors influencing their expansion are poorly understood. This study aimed to review systematically published... (Review)
Review
OBJECTIVE/BACKGROUND
The growth rates of thoracic aortic aneurysms (TAAs) and factors influencing their expansion are poorly understood. This study aimed to review systematically published literature describing TAA expansion and examine factors that may be associated with this.
METHODS
A comprehensive search of MEDLINE and Embase databases was performed until 30 April 2015. Studies describing rates of TAA growth were identified and systematically reviewed. Outcomes of interest were TAA growth rates and associated factors. Study quality was assessed using Scottish Intercollegiate Guidelines Network quality checklists for cohort studies.
RESULTS
Eleven publications, involving 1383 patients, met the eligibility criteria and were included in the review. Included studies were generally low in quality. Aneurysm measurement and growth-rate estimation techniques were inconsistently reported. Mean growth rates for all TAAs ranged from 0.2 to 4.2 mm/year. Mean growth rates for ascending and aortic arch aneurysms ranged from 0.2 to 2.8 mm/year, while those for descending and thoracoabdominal aneurysms ranged from 1.9 to 3.4 mm/year in studies reporting according to anatomical location. Large aneurysm size, distal aneurysm locations, presence of Marfan's syndrome, and bicuspid aortic valve were consistently associated with accelerated TAA growth. Presence of chronic dissection and chronic obstructive pulmonary disorder were also implicated as risk factors for faster TAA growth. Associations between medical comorbidity and aneurysm expansion were conflicting. Previous aortic surgery and anticoagulants were reported to have a protective effect on aneurysm growth in two studies.
CONCLUSION
There is a shortfall in the understanding of TAA expansion rates. Existing studies are heterogeneous in methodology and reported outcomes. Identified unifying themes suggest that TAAs grow at a slow rate with large presenting diameter, distal aneurysm, and history of bicuspid aortic valve or Marfan's syndrome serving as main risk factors for accelerated aneurysm growth. High-quality studies with a standardised approach to TAA growth assessment are required.
Topics: Aortic Aneurysm, Thoracic; Disease Progression; Humans; Risk Factors
PubMed: 26947541
DOI: 10.1016/j.ejvs.2016.01.017 -
Journal of Vascular Surgery Mar 2023To provide an updated systematic literature review summarizing current evidence on aortic neck dilatation (AND) after endovascular aortic aneurysm repair (EVAR) in... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To provide an updated systematic literature review summarizing current evidence on aortic neck dilatation (AND) after endovascular aortic aneurysm repair (EVAR) in patients with infrarenal abdominal aortic aneurysm.
METHODS
An extensive electronic search in major electronic databases was conducted between January 2000 and December 2021. Eligible for inclusion were observational studies that followed up with patients (n ≥ 20) undergoing EVAR with self-expanding endografts, for 12 or more months, evaluated AND with computed tomography angiography and provided data on relevant outcomes. The primary end point was the incidence of AND after EVAR, and the secondary end points were the occurrence of type Ia endoleak, stent graft migration, secondary rupture, and reintervention.
RESULTS
We included 34 studies with a total sample of 12,038 patients (10,413 men; median age, 71 years). AND was defined clearly in 18 studies, but significant differences in AND definition were evidenced. The pooled incidence of AND based on quantitative analysis of 16 studies with a total of 9201 patients (7961 men; median age, 72 years) was calculated at 22.9% (95% confidence interval [CI], 14.4-34.4) over a follow-up period ranging from 12 months to 14 years. The risk of a type Ia endoleak was significantly higher in AND patients compared with those without AND (odds ratio, 2.95; 95% CI, 1.10-7.93; P = .030). Similarly, endograft migration was more common in the AND group compared with the non-AND group (odds ratio, 5.95; 95% CI, 1.80-19.69; P = .004). The combined incidence of secondary rupture and reintervention did not differ significantly between the two groups, even though the combined effect was in favor of the non-AND group.
CONCLUSIONS
Proximal AND after EVAR is common and occurs in a large proportion of patients with infrarenal abdominal aortic aneurysm. AND can influence the long-term durability of proximal endograft fixation and is significantly related to adverse outcomes, often leading to reinterventions.
Topics: Male; Humans; Aged; Blood Vessel Prosthesis Implantation; Endoleak; Treatment Outcome; Dilatation; Risk Factors; Endovascular Procedures; Retrospective Studies; Aortic Aneurysm, Abdominal; Blood Vessel Prosthesis
PubMed: 35948244
DOI: 10.1016/j.jvs.2022.07.182 -
Prevalence and Epidemiological Pattern of Abdominal Aortic Aneurysms in Africa: A Systematic Review.Journal of the West African College of... 2020The incidence of abdominal aortic aneurysms (AAAs) in high-income countries has been declining in the last three decades. However, in most low-income and middle-income... (Review)
Review
INTRODUCTION
The incidence of abdominal aortic aneurysms (AAAs) in high-income countries has been declining in the last three decades. However, in most low-income and middle-income countries especially in Africa, little is known about its burden. The absence of screening services for AAA in African countries makes it difficult to detect and promptly manage AAA before rupture, which has significant implications for mortality. This study sought to systematically assess the prevalence of AAA amongst patients visiting hospitals in Africa and evaluate its epidemiological pattern.
MATERIALS AND METHODS
A systematic review was performed on the EMBASE, GLOBAL HEALTH, MEDLINE, and PUBMED databases. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement standards and protocol registered with PROSPERO (CRD42020162214). A data extraction tool was used to get relevant information from these studies. Quality assessment and risk of bias were performed using the Newcastle Ottawa Scale for cross-sectional studies. Results were summarised in tables, figures, and a forest plot. A narrative synthesis approach of the articles was taken.
RESULTS
Two hundred and sixty-one studies were identified and after the exclusion of 246, a final 15 were deemed suitable for analysis. A total of 4012 participants were screened for AAA and of these, 129 cases were identified. The prevalence of AAA in these studies ranged from 0.7 to 6.4%. Male participants accounted for 115 (89.1%) of the cases. There was a wide age range (31-72 years) reflective of both its possible infective and degenerative aetiology. AAA was reported to be associated with hypertension, smoking, advanced age, coronary artery disease, and HIV infection. There was no association between AAA and diabetes. Over 50% of cases were identified incidentally. About one-third (23-54%) of the participants presented aortic rupture with a mortality rate ranging between 65 and 72%.
CONCLUSIONS
AAA prevalence in Africa is probably higher than the current thinking as there is no baseline data to compare with. Aetiologically, AAA was shown to be associated with hypertension, smoking, coronary artery disease, and possibly infectious pathologies like HIV. Large epidemiological studies would help better characterise AAA in this setting. Lastly, efforts targeting the reduction of the risk factors for AAA would go a long way in reducing the burden of AAA.
PubMed: 35531585
DOI: 10.4103/jwas.jwas_15_21 -
Journal of the American Heart... Oct 2018Background There are no recognized pharmacological treatments for abdominal aortic aneurysms ( AAA ), although statins are suggested to be beneficial. We sought to... (Meta-Analysis)
Meta-Analysis
Background There are no recognized pharmacological treatments for abdominal aortic aneurysms ( AAA ), although statins are suggested to be beneficial. We sought to summarize the literature regarding the effects of statins on human AAA growth, rupture, and 30-day mortality. Methods and Results We conducted a systematic review and meta-analysis of randomized and observational studies using the Cochrane CENTRAL database, MEDLINE , and EMBASE up to June 15, 2018. Review, abstraction, and quality assessment were conducted by 2 independent reviewers, and a third author resolved discrepancies. Pooled mean differences and odds ratios with 95% confidence intervals were calculated using random effects models. Heterogeneity was quantified using the I statistic, and publication bias was assessed using funnel plots. Our search yielded 911 articles. One case-control and 21 cohort studies involving 80 428 patients were included. The risk of bias was low to moderate. Statin use was associated with a mean AAA growth rate reduction of 0.82 mm/y (95% confidence interval 0.33, 1.32, P=0.001, I=86%). Statins were also associated with a lower rupture risk (odds ratio 0.63, 95% confidence interval 0.51, 0.78, P<0.0001, I=27%), and preoperative statin use was associated with a lower 30-day mortality following elective AAA repair (odds ratio 0.55, 95% confidence interval 0.36, 0.83, P=0.005, I=57%). Conclusions Statin therapy may be associated with reduction in AAA progression, rupture, and lower rates of perioperative mortality following elective AAA repair. These data argue for widespread statin use in AAA patients. Clinical Trial Registration URL : www.crd.york.ac.uk . Unique identifier: CRD 42017056480.
Topics: Aneurysm, Ruptured; Aortic Aneurysm, Abdominal; Disease Progression; Global Health; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Perioperative Care; Survival Rate; Vascular Surgical Procedures
PubMed: 30371297
DOI: 10.1161/JAHA.118.008657 -
European Journal of Vascular and... Mar 2014Epidemiologic evidence suggests that patients with diabetes may have a lower incidence of abdominal aortic aneurysm (AAA); however, the link between diabetes and AAA... (Review)
Review
Epidemiologic evidence suggests that patients with diabetes may have a lower incidence of abdominal aortic aneurysm (AAA); however, the link between diabetes and AAA development and expansion is unclear. The aim of this review is to analyze updated evidence to better understand the impact of diabetes on prevalence, incidence, clinical outcome, and expansion rate of AAA. A systematic review of literature published in the last 20 years using the PubMed and Cochrane databases was undertaken. Studies reporting appropriate data were identified and a meta-analysis performed using the generic inverse variance method. Sixty-four studies were identified. Methodological quality was "fair" in 16 and "good" in 44 studies according to a formal assessment checklist (Newcastle-Ottawa). In 17 large population prevalence studies there was a significant inverse association between diabetes and AAA: pooled odds ratio (OR) 0.80; 95% confidence intervals (CI) 0.70-0.90 (p = .0009). An inverse association was also confirmed by pooled analysis of data from smaller prevalence studies on selected populations (OR 0.59; 95% CI 0.35-0.99; p = .05), while no significant results were provided by case-control studies. A significant lower pooled incidence of new AAA in diabetics was found over six prospective studies: OR 0.54; 95% CI 0.31-0.91; p = .03. Diabetic patients showed increased operative (30-day/in-hospital) mortality after AAA repair: pooled OR 1.26; 95% CI 1.10-1.44; p = .0008. The increased operative risk was more evident in studies with 30-day assessment. In the long-term, diabetics showed lower survival rates at 2-5 years, while there was general evidence of lower growth rates of small AAA in patients with diabetes compared to non-diabetics. There is currently evidence to support an inverse relationship between diabetes and AAA development and enlargement, even though fair methodological quality or unclear risk of bias in many available studies decreases the strength of the finding. At the same time, operative and long-term survival is lower in diabetic patients, suggesting increased cardiovascular burden. The higher mortality in diabetics raises the question as to whether AAA repair should be individualized in selected diabetic populations at higher AAA rupture risk.
Topics: Aortic Aneurysm, Abdominal; Aortic Rupture; Diabetes Mellitus; Diabetic Angiopathies; Hospital Mortality; Humans; Mass Screening; Odds Ratio; Prevalence; Risk Assessment
PubMed: 24447529
DOI: 10.1016/j.ejvs.2013.12.007 -
Journal of the American Heart... Apr 2021Background Prior studies have suggested aortic peak wall stress (PWS) and peak wall rupture index (PWRI) can estimate the rupture risk of an abdominal aortic aneurysm... (Meta-Analysis)
Meta-Analysis
Background Prior studies have suggested aortic peak wall stress (PWS) and peak wall rupture index (PWRI) can estimate the rupture risk of an abdominal aortic aneurysm (AAA), but whether these measurements have independent predictive ability over assessing AAA diameter alone is unclear. The aim of this systematic review was to compare PWS and PWRI in participants with ruptured and asymptomatic intact AAAs of similar diameter. Methods and Results Web of Science, Scopus, Medline, and The Cochrane Library were systematically searched to identify studies assessing PWS and PWRI in ruptured and asymptomatic intact AAAs of similar diameter. Random-effects meta-analyses were performed using inverse variance-weighted methods. Leave-one-out sensitivity analyses were conducted to assess the robustness of findings. Risk of bias was assessed using a modification of the Newcastle-Ottawa scale and standard quality assessment criteria for evaluating primary research papers. Seven case-control studies involving 309 participants were included. Meta-analyses suggested that PWRI (standardized mean difference, 0.42; 95% CI, 0.14-0.70; =0.004) but not PWS (standardized mean difference, 0.13; 95% CI, -0.18 to 0.44; =0.418) was greater in ruptured than intact AAAs. Sensitivity analyses suggested that the findings were not dependent on the inclusion of any single study. The included studies were assessed to have a medium to high risk of bias. Conclusions Based on limited evidence, this study suggested that PWRI, but not PWS, is greater in ruptured than asymptomatic intact AAAs of similar maximum aortic diameter.
Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Aortography; Asymptomatic Diseases; Biomechanical Phenomena; Humans
PubMed: 33855866
DOI: 10.1161/JAHA.120.019772 -
Journal of Vascular Surgery Sep 2018Outcomes after repair of ruptured abdominal aortic aneurysm (RAAA) have improved in the last decade. It is unknown whether this has resulted in a reduction of... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
Outcomes after repair of ruptured abdominal aortic aneurysm (RAAA) have improved in the last decade. It is unknown whether this has resulted in a reduction of postoperative bowel ischemia (BI). The primary objective was to determine BI prevalence after RAAA repair. Secondary objectives were to determine its major sequelae and differences between open repair (OR) and endovascular aneurysm repair (EVAR).
METHODS
This systematic review (PROSPERO CRD42017055920) followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. MEDLINE and Embase were searched for studies published from 2005 until 2018. The methodologic quality of observational studies was assessed with the Methodological Index for Non-Randomized Studies (MINORS) tool. The quality of the randomized controlled trials (RCTs) was assessed with the Cochrane Collaboration's tool for assessing risk of bias. BI prevalence and rates of BI as cause of death, reoperation, and bowel resection were estimated with meta-analyses with a random-effects model. Differences between OR and EVAR were estimated with pooled risk ratios with 95% confidence intervals (CIs). Changes over time were assessed with Spearman rank test (ρ). Publication bias was assessed with a funnel plot analysis.
RESULTS
A total of 101 studies with 52,670 patients were included; 72 studies were retrospective cohort studies, 14 studies were prospective cohort studies, 12 studies were retrospective administrative database studies, and 3 studies were RCTs. The overall methodologic quality of the RCTs was high, but that of observational studies was low. The pooled prevalence of BI ranged from of 0.08 (95% CI, 0.07-0.09) in database studies to 0.10 (95% CI, 0.08-0.12) in cohort studies. The risk of BI was higher after OR than after EVAR (risk ratio, 1.79; 95% CI, 1.25-2.57). The pooled rate of BI as cause of death was 0.04 (95% CI, 0.03-0.05), and that of BI as cause of reoperation and bowel resection ranged between 0.05 and 0.07. BI prevalence did not change over time (ρ, -0.01; P = .93). The funnel plot analysis was highly suggestive of publication bias.
CONCLUSIONS
The prevalence of clinically relevant BI after RAAA repair is approximately 10%. Approximately 5% of patients undergoing RAAA repair suffer from severe consequences of BI. BI is less prevalent after EVAR than after OR.
Topics: Aortic Aneurysm, Abdominal; Aortic Rupture; Humans; Intestines; Ischemia; Postoperative Complications; Risk Factors
PubMed: 30146037
DOI: 10.1016/j.jvs.2018.05.018 -
Current Cardiology Reviews 2021Aortic aneurysms are worrisome because of their predisposition to dissection and rupture. Beta-blockers are considered first-line therapy for aortic aneurysms. The... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Aortic aneurysms are worrisome because of their predisposition to dissection and rupture. Beta-blockers are considered first-line therapy for aortic aneurysms. The following meta-analysis assesses if beta-blockers diminish aortic aneurysm growth.
METHODS
A literature search was performed to collect information on clinical trials that have assessed aortic aneurysm growth between beta-blockers and placebo. The primary endpoint was aortic aneurysm growth rate per year. A forest plot with a random-effects model was used for analysis.
RESULTS
Eight clinical trials were included in the analysis. Beta-blockers showed a statistically non-significant effect on aortic aneurysm growth (standard mean difference -0.44; 95% CI [-0.44, 0.00]).
CONCLUSION
Beta-blockers do not significantly influence aortic aneurysm growth. Further studies are required to find a suitable medical therapy to reduce growth rates.
Topics: Adrenergic beta-Antagonists; Aortic Aneurysm, Abdominal; Humans
PubMed: 33143615
DOI: 10.2174/1573403X16999201102213619 -
Journal of Vascular Surgery Aug 2022Clostridium septicum bacteremia is often associated with occult malignancies (approximately 80%), especially of the right colon. Furthermore, inflammation of the aortic... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Clostridium septicum bacteremia is often associated with occult malignancies (approximately 80%), especially of the right colon. Furthermore, inflammation of the aortic wall can rapidly lead to aneurysm induction through bacterial seeding into atheromatous lesions with consecutive life-threatening rupture. We summarize all published data on this rare and lethal disease to evaluate therapeutic approaches and give valid treatment recommendations because there are no guidelines.
METHODS
A systematic review of the literature was conducted screening EMBASE and MEDLINE databases following the PRISMA guidelines with search period from first description to August 25, 2021.
RESULTS
There were 72 cases of C septicum aortitis reported in 64 publications. Endovascular aortic repair (EVAR) was performed in a minority of patients (n = 6) unfit for surgery but lacked long-term survivors. Antibiotic treatment was beneficial in a bridge to surgery concept, but up to now harbored a 6-month mortality rate of 100% (median overall survival, 0.5 months) when no additional aortic repair was performed. Open aortic repair was the only potential curative approach but was accompanied with a 90-day-mortality of 26.7% (4/15).
CONCLUSIONS
Open aortic repair combined with perioperative antibiotic treatment should be offered to all patients as the only potentially curative approach. If applicable, resection of a coexisting colonic tumor should be performed after successful aortic repair. Alternatively, long-term antibiotic treatment can be offered to patients unfit for surgery in a palliative setting. Endovascular aortic repair has been performed on a minority of patients with a high risk for stent graft infection and should remain a salvage strategy when therapeutic pressure demands acute intervention in patients unfit for surgery.
Topics: Anti-Bacterial Agents; Aorta; Aortic Aneurysm, Abdominal; Aortitis; Blood Vessel Prosthesis Implantation; Clostridium septicum; Endovascular Procedures; Humans; Stents; Treatment Outcome
PubMed: 35358668
DOI: 10.1016/j.jvs.2022.02.029