The treatment of bilateral popliteal artery entrapment syndrome with nonuniform symptoms: A case report and literature review

Popliteal artery entrapment syndrome (PAES) is a rare vascular disease, and cases of bilateral PAES associated with distinct symptoms in each of the affected legs are very rare. In an effort to improve current understanding regarding the presentation and treatment of this condition, a case of bilateral PAES is herein described with a corresponding review of the associated literature. The overall process of diagnosing and treating one patient affected by bilateral PAES was retrospectively assessed to provide comprehensive insight regarding this disease. This patient was diagnosed via contrast-enhanced computed tomography (CT), and right-sided symptomatic PAES was successfully treated via autogenous saphenous venous graft arterial bypass surgery. In contrast, the asymptomatic left-sided PAES in this patient was subject to close follow-up monitoring. Over a 2-year postoperative follow-up period, this patient did not experience any symptoms or complications. As such, autogenous saphenous venous graft arterial bypass surgery represents a safe and efficacious means of treating PAES, whereas surgery may not be required for cases of asymptomatic PAES even in patients with a bilateral presentation.

Sex differences in outcomes after revascularization for acute lower limb ischemia: Propensity score adjusted analysis

BACKGROUND

Previous reports have suggested higher rates of mortality and amputation for female patients in acute lower limb ischemia (ALI). The aims of the present study were to investigate if there is a difference in mortality, amputation, and fasciotomy between the sexes.

METHODS

A retrospective cohort study of consecutive patients undergoing index revascularization for ALI between 2001 and 2018 was conducted. A propensity score was created through a logistic regression with female/male sex as an outcome. Cox regression analyses for 90-day and 1-year mortality, combining major amputation/mortality, and logistic regression for major bleeding and fasciotomy, were performed. All analyses were performed with and without adjusting for propensity score.

RESULTS

A total of 709 patients were included in the study of which 45.9% were women. Mean age was 72.1 years. Females were older and had higher rates of atrial fibrillation, embolic disease, and lower estimated glomerular filtration rate, while men more often had anemia and chronic peripheral arterial disease. Mortality at 1 year was 21.2% for women and 14.7% for men. The adjusted hazard ratio for 1-year mortality was 0.99 (95% CI 0.67-1.46). Fasciotomy was performed in 7.1% of female and 12.8% of male patients; the adjusted odds ratio was 0.52 (95% CI 0.29-0.91).

CONCLUSION

Sex was not found to be an independent risk factor for mortality or combined major amputation/mortality after revascularization for acute lower limb ischemia, whereas women had lower odds of undergoing fasciotomy. Whether women are underdiagnosed or do not develop acute compartment syndrome in the lower leg as often as men should be evaluated prospectively.

Endoleak following endovascular repair of popliteal artery aneurysm: clinical outcome and contrast-enhanced ultrasound detection

BACKGROUND

Continued blood flow in the aneurysm sac after repair, also known as endoleak, can occur after both open and endovascular popliteal aneurysm repair (EPAR) with risk for aneurysm sac enlargement. Primary aims were to investigate aneurysm sac growth and the presence and classification of endoleak after EPAR using contrast-enhanced ultrasound (CEUS).

METHODS

Cross-sectional study of patients receiving EPAR with expanded polytetrafluorethylene (ePTFE) covered stent-grafts between 1^st of January 2009 and 1^st of February 2019 at a tertiary referral endovascular center. Patients were re-invited in 2021 and 31 legs were examined for endoleak using CEUS. Endoleaks were classified by a core-lab consisting of three CEUS-experienced physicians.

RESULTS

Median follow-up was 57 months (range 33-143 months). Endoleak was detected in 16 PAA, and categorized as type I (N.=3), type II (N.=10), type III (N.=1) or indeterminate (N.=2). Median maximal PAA diameter was 24 mm (range 15-55 mm) at the time of EPAR compared to 17 mm (range 6-43 mm) at follow-up (P<.001). Maximal aneurysm sac diameter was smaller at follow-up than at the index procedure in both PAAs with and without endoleak on CEUS (P=0.005 vs. P<0.001, respectively). There was no difference in PAA sac shrinkage at follow-up between patients with or without endoleak (P=0.28). Freedom from aneurysm sac growth was 97%.

CONCLUSIONS

CEUS was sensitive in endoleak detection after EPAR. Shrinkage of the PAA sac was found in both patients with and without endoleaks. CEUS appears useful for targeted examinations rather than routine surveillance after EPAR.

Open Repair versus Endovascular Repair in The Treatment of Symptomatic Popliteal Artery Aneurysms

OBJECTIVE

Endovascular and open surgical modalities are currently used to treat popliteal artery aneurysms (PAA). However, there is limited data on the comparative durability of both repairs to guide physicians especially in the treatment of patients presenting symptomatic. We aimed to study the comparative effectiveness of endovascular PAA repair (EPAR) versus open PAA repair (OPAR).

METHODS

The vascular quality initiative (VQI)-Medicare linked database was queried for patients with symptomatic PAA who underwent OPAR or EPAR from January 2010 to December 2018. Kaplan-Meier estimates, log rank tests and multivariable Cox proportional hazard regression were employed to study the outcomes of amputation free survival (AFS), freedom from major amputation, and overall survival in 2 years following the index procedure.

RESULTS

A total of 1375 patients were studied, of which 23.7% (n=326) were treated with EPAR. Patients treated with OPAR were younger, less likely to have coronary artery disease (CAD) and chronic kidney disease (CKD), but more likely to be smokers and to present with acute lower extremity ischemia. OPAR patients had better 2-year AFS (84.5% vs. 72.5%, P<0.001) and overall survival (86.2% vs 74.7%, P<0.001). Freedom from major amputation at 2 years was comparable between EPAR and OPAR (95.5% vs 97.7%, P=0.164) in the overall cohort. Within the sub cohort of patients with acute limb ischemia, freedom from major amputation was significantly higher for OPAR compared to EPAR (97.4% vs. 90.6%, P=0.021). After adjustment for confounders, OPAR was associated with decreased risk of amputation or death (aHR, 0.62; 95%CI, 0.48-0.80; P<0.001) and mortality (aHR, 0.63; 95%CI, 0.48-0.81; P<0.001) at 2 years. OPAR and EPAR had comparable adjusted risk of 2-year major amputation in the overall cohort. However, for patients presenting with acute limb ischemia OPAR was associated with 72% lower risk of 2-year major amputation compared to EPAR (aHR, 0.28; 95%CI, 0.10-0.83; P=0.021).

CONCLUSION

In this multi-institutional observational study of symptomatic popliteal aneurysms, OPAR was associated with significantly better amputation free and overall survival compared to EPAR. For patients with acute ischemia, OPAR was associated with reduced risk of amputation. These findings suggest that OPAR may be superior to EPAR in the treatment of symptomatic PAA. A consideration of OPAR as first line definitive treatment for symptomatic PAA patients who are good surgical candidates is suggested.

A systematic review and meta-analysis of treatment and natural history of popliteal artery aneurysms

OBJECTIVE

To summarize the best available evidence comparing open vs endovascular popliteal artery aneurysm (PAA) repair. We also summarized the natural history of PAAs to support of the Society for Vascular Surgery guidelines.

METHODS

We searched MEDLINE, EMBASE, Cochrane databases, and Scopus for studies of patients with PAAs treated with an open vs an endovascular approach. We also included studies of natural history of untreated patients. Studies were selected and appraised by pairs of independent reviewers. A meta-analysis was performed when appropriate.

RESULTS

We identified 32 original studies and 4 systematic reviews from 2191 candidate references. Meta-analysis showed that compared with the endovascular approach, open surgical repair was associated with higher primary patency at 1 year (odds ratio [OR], 2.10; 95% confidence interval [CI], 1.41-3.12), lower occlusion rate at 30 days (OR, 0.41; 95% CI, 0.24-0.68) and fewer reinterventions (OR, 0.28; 95% CI, 0.17-0.45), but a longer hospital stay (standardized mean difference, 2.16; 95% CI, 1.23-3.09) and more wound complications (OR, 5.18; 95% CI, 2.19-12.26). There was no statistically significant difference in primary patency at 3 years (OR, 1.38; 95% CI, 0.97-1.97), secondary patency (OR, 1.59; 95% CI, 0.84-3.03), mortality at the longest follow-up (OR, 0.49; 95% CI, 0.21-1.17), mortality at 30 days (OR, 0.28; 95% CI, 0.06-1.36), or amputation (incidence rate ratio, 0.85; 95% CI, 0.56-1.31). The certainty in these estimates was, in general, low. Studies of PAA natural history suggest that thromboembolic complications and amputation develop at a mean observation time of 18 months and they are frequent. One study showed that at 5 years, approximately one-half of the patients had complications.

CONCLUSIONS

This systematic review provides event rates for outcomes important to patients with PAAs. Despite the low certainty of the evidence, these rates along with surgical expertise and anatomic feasibility can help patients and surgeons to engage in shared decision-making.

Poor runoff and distal coverage below the knee are associated with poor long-term outcomes following endovascular popliteal aneurysm repair

OBJECTIVE

Reports of good short-term outcomes for endovascular repair of popliteal artery aneurysms have led to an increased use of the technique. However, data are lacking on long-term limb-related outcomes and factors associated with the failure of endovascular repair.

METHODS

All patients who underwent endovascular popliteal aneurysm repair (EPAR) at a single institution from January 2006 to December 2018 were included in the study. Demographics, indications, anatomic and operative details, and outcomes were reviewed. Long-term patency, major adverse limb event-free survival (MALE-FS) and graft loss/occlusion were analyzed with multivariable cox regression analysis and Kaplan-Meier curves.

RESULTS

We included 117 limbs from 101 patients with a mean follow-up of 55.6 months (range, 0.43-158 months). The average age was 73 ± 9.3 years. Thirty-two patients (29.1%) were symptomatic (claudication, rest pain, tissue loss, or rupture). The stent grafts crossed the knee joint in 91.4% of cases. In all, 36.8% of procedures used one stent graft, 41.0% used two stent grafts, and 22.2% of procedures used more than two stent grafts. The median arterial length covered was 100 mm, with an average length of stent overlap of 25 mm. Tapered configurations were used in 43.8% of cases. The majority of limbs (62.8%) had a three-vessel runoff, 20.2% had a two-vessel runoff, and 17% has a one-vessel runoff. The Kaplan-Meier estimates of graft occlusion at 1 and 3 years were 6.3% and 16.2%, respectively. The 1- and 3-year primary patency rates were 88.2% and 72.6%, and the 1- and 3-year major adverse limb event-free survival (MALE-FS) rates were 82% and 57.4%. The 1- and 3-year survival rates were 92.9% and 76.2%, respectively. On multivariable Cox regression, aneurysm size, one-vessel runoff, and coverage below the knee were associated with a lower 3-year MALE-FS. Coverage below the knee was also associated with a lower 3-year MALE-FS. Other anatomic or technical details were not associated with limb-related events or patency.

CONCLUSIONS

This study is the largest single center analysis to describe the predictors of poor outcomes after EPAR. EPAR is a safe and effective way to treat popliteal artery aneurysms. Factors associated with poor MALE-FS after EPAR include single-vessel tibial runoff and coverage below the knee.

Adherence to instruction for use after endovascular repair of popliteal artery aneurysm

OBJECTIVES

Endovascular repair (ER) of popliteal artery aneurysm (PAA) is an alternative to open repair. However, there is no standardized protocol for when to opt for ER and the decision is therefore at the discretion of the clinician. This study aims to evaluate the adherence to the Instruction For Use (IFU) in patients undergoing ER for PAA and factors associated with stent graft patency at one year.

METHODS

The adherence to IFU provided by the manufacturer in 55 patients treated with Gore Viabahn® Endoprosthesis with Heparin Bioactive Surface for PAA between 2009 and 2019 were retrospectively analyzed. Duplex follow-up was performed at 30 days and one year.

RESULTS

The two groups of patients treated within (n = 10) and not within (n = 45) IFU did not differ in patient demographics, diagnostic assessment, treatment or outcome. Forty-five patients (81.8%) received stent graft placement with at least one deviation according to IFU. Distal oversizing >20% was the most frequent deviation against IFU (n = 22, 40.0%). Primary patency at one year was 72%. Diameter size difference >1 mm between overlapping stent grafts (6/14 [43%], p = 0.013) and renal insufficiency (5/12 [42%], p = 0.0086) were associated with lower primary patency at one year. Age-adjusted analysis of tortuosity index (HR 1.78/SD, 95% CI 1.17-2.71; p = 0.0071) and maximal PAA angle (HR 1.73/SD, 95% CI 1.018-2.95; p = 0.043) were associated with major amputation/mortality at end of follow-up.

CONCLUSION

The majority of patients undergoing ER for PAA were not treated within IFU. Diameter size difference >1 mm between overlapping stent grafts was associated with a higher loss of primary patency at one year. Multi-center studies with larger sample size and long-term follow up of patency are warranted.

Risk Factors for Fasciotomy After Revascularization for Acute Lower Limb Ischaemia

Background: Acute lower limb ischaemia (ALI) is a life and limb threatening vascular emergency. Acute compartment syndrome (ACS) may develop upon revascularization. The risk of fasciotomy was hypothesized to be decreased in women due to their lower calf muscle mass. The main aim was to evaluate risk factors for fasciotomy after revascularization for ALI.

Methods: This is a retrospective observational study of patients undergoing revascularization for ALI between 2001 and 2018. Factors associated with outcome at 1 year in univariable analysis (p < 0.1) were chosen for multi-variable analysis and expressed in Odds Ratios (OR) with 95% confidence intervals (CI).

Results: The median age for women (n = 394) was 75 years and men (n = 449) was 70 years (p < 0.001). The frequency of fasciotomy was 10.0% (84/843). The median in-hospital stay was 28 vs. 6 days for patients undergoing fasciotomy and not, respectively (p < 0.001). In adjusted analysis, renal insufficiency (OR 1.77, 95% CI 1.04–3.01), motor deficit (OR 4.40, 95% CI 2.45–7.92), popliteal artery aneurysm thromboembolism (OR 2.26, 95% CI 1.06–4.80), and open vascular surgery (OR 3.43, 95% CI 1.97–5.98) were associated with an increased risk of fasciotomy. Female patients (OR 0.49, 95% CI 0.28–0.84) and anemia (OR 0.52, 95% CI 0.28–0.84) had a lower risk. The major amputation/mortality rate at 1-year was 27.7%; fasciotomy (OR 1.94, 95% CI 1.11–3.40), anemia (OR 1.84, 95% CI 1.24–2.73) and female gender (OR 1.44, 95% CI 1.00–2.08) were independently associated with an increased risk.

Conclusions: Female patients had lower rates of fasciotomies, but subsequent higher risk of major amputation/mortality, which may be attributed to inferior results of revascularization. Lower muscle mass and underdiagnosis of ACS could also explain the lower frequency of fasciotomy for female patients. Further studies are needed to better understand gender differences in presentation of ALI, revascularization results and diagnosis of ACS.

Editor's Choice - Regional Versus General Anaesthesia in Peripheral Vascular Surgery: a Propensity Score Matched Nationwide Cohort Study of 17 359 Procedures in Denmark

OBJECTIVE

Cardiopulmonary comorbidity is common in vascular surgery. General anaesthesia (GA) may impair perfusion and induce respiratory depression. Regional anaesthesia (RA), including neuraxial or peripheral nerve blocks, may therefore be associated with a better outcome.

METHODS

This was a nationwide retrospective cohort study. All open inguinal and infra-inguinal arterial surgical reconstructions from 2005 to 2017 were included. Data were extracted from national registries. Multivariable linear and logistic regression models and propensity score matching were used. The propensity score was derived by developing a model that predicted the probability that a given patient would receive GA based on age, comorbidity, anticoagulant medication, procedure type, and the urgency of surgery. Matching was performed in four groups based on American Society of Anesthesiologists' score I - II, score III - V, and gender. Outcome parameters included surgical and general complications (bleeding, thrombosis/embolus, cardiac, pulmonary, renal, cerebral, and >3 days intensive care therapy), length of stay, and 30 day mortality, hypothesising a better outcome after RA.

RESULTS

There were 10 509 procedures in the GA group and 6 850 in the RA group. After propensity score matching, 6 267 procedures were included in each group. Surgical and general complications were significantly more common after GA in both matched (3.8 vs. 2.5%, p < .001 and 6.5 vs. 4.2%, p < .001) and unmatched analyses (3.8 vs. 2.5%, p < .001 and 6.5 vs. 4.2%, p < .001). The 30 day mortality rate was significantly higher after GA, in matched and un matched analyses (3.1 vs. 2.4%, p = .019 and 4.1 vs. 2.4%, p < .001). There was no difference in length of stay.

CONCLUSION

RA may be associated with a better outcome, compared with GA, after open inguinal and infra-inguinal peripheral vascular surgery. In the clinical context when RA is not feasible, GA can still be considered safe.

A Comparison of Endovascular Versus Open Repair of Popliteal Artery Aneurysms: An Updated Meta-Analysis

OBJECTIVE

Traditionally, popliteal artery aneurysms (PPAs) were treated via open repair (OR). However, more recently endovascular repair (EVR) approaches have become more common for the treatment of PPAs. The present meta-analysis therefore sought to conduct an up-to-date review of studies comparing the relative safety and efficacy of these 2 repair strategies. To that end, patient outcomes including primary patency, operating time, hospital stay duration, and re-intervention, amputation, and graft occlusion within 30 days were compared for these OR and EVR approaches.

METHODS

Studies in which OR and EVR were compared as treatments for PPAs were identified through systematic searching of the PubMed and Embase databases. Any studies either analyzing only one of these treatments in isolation or analyzing <5 patients were not included in this analysis. For all relevant studies, patient demographic information and outcome details were compiled. Risk of bias was analyzed using a modified Newcastle-Ottawa Scale. The odds ratios, mean differences, and hazard ratios (HRs) for patient outcomes were estimated using a random-effects model.

RESULTS

In total, we identified 17 relevant studies including a single randomized controlled trial and 16 retrospective cohort studies, incorporating 6887 total cases (1662 EVR and 5225 OR). The quality of evidence for all measured outcomes was deemed to be very low or low according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. Rates of primary patency were found to be significantly higher for patients treated via OR relative to those treated via EVR (HR = 1.60; 95% confidence interval [CI]: 1.12-2.30; P = .03). Operative and hospitalization durations, in contrast, were significantly lower for patients treated via EVR. Patients treated via EVR also experienced significantly higher rates of graft thrombosis and reintervention within 30 days relative to patients treated via OR. However, no significant differences were observed between treatments with respect to rates of patient amputation (OR = 1.01; 95% CI: 0.55-1.85; P = .98).

CONCLUSIONS

The available data suggest that PPA repair via EVR is a safe alternative to OR, but that short-term graft thrombosis and reintervention rates are significantly greater for the former approach. Moreover, few studies to date have compared these techniques and those that were largely retrospective in nature with relatively low-quality evidence, making it difficult to make definitive statements regarding the relative safety and efficacy of these 2 repair strategies. Additional population-based large-scale studies are therefore essential in order to conduct a robust evaluation of the safety and utility of EVR as an alternative to OR for PPA repair.

Endovascular versus open repair of asymptomatic popliteal artery aneurysm

BACKGROUND

Popliteal artery aneurysm (PAA) is a focal dilatation and weakening of the popliteal artery. If left untreated, the aneurysm may thrombose, rupture or the clot within the aneurysm may embolise causing severe morbidity. PAA may be treated surgically by performing a bypass from the arterial segment proximal to the aneurysm to the arterial segment below the aneurysm, which excludes the aneurysm from the circulation. It may also be treated by a stent graft that is inserted percutaneously or through a small cut in the groin. The success of the procedure is gauged by the ability of the graft to stay patent over an extended duration. While surgical treatment is usually preferred in an emergency, the evidence on first line treatment in a non-emergency setting is unclear. This is an update of a review first published in 2014.

OBJECTIVES

To assess the effectiveness of an endovascular stent graft versus conventional open surgery for the treatment of asymptomatic popliteal artery aneurysms (PAA) on primary and assisted patency rates, hospital stay, length of the procedure and local complications.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 29 January 2019.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing endovascular stent grafting versus conventional open surgical repair in patients undergoing unilateral or bilateral prophylactic repair of asymptomatic PAAs.

DATA COLLECTION AND ANALYSIS

We collected data on primary and assisted primary patency rates (primary endpoints) as well as operating time, the length of hospital stay, limb salvage and local wound complications (secondary endpoints). We presented results as risk ratio or mean difference with 95% confidence intervals and assessed the certainty of the evidence using GRADE.

MAIN RESULTS

No new studies were identified for this update. A single RCT with a total of 30 PAAs met the inclusion criteria. There was a low risk of selection bias and detection bias. However, the risks of performance bias, attrition bias and reporting bias were unclear from the study. Despite being an RCT, the certainty of the evidence was downgraded to moderate due to the small sample size, resulting in wide confidence intervals (CIs); only 30 PAAs were randomised over a period of five years (15 PAAs each in the groups receiving endovascular stent graft and undergoing conventional open surgery). The primary patency rate at one year was 93.3% in the endovascular group and 100% in the surgery group (RR 0.94, 95% CI 0.78 to 1.12; moderate-certainty evidence). The assisted patency rate at one year was similar in both groups (RR 1.00, 95% CI 0.88 to 1.13; moderate-certainty evidence). There was no clear evidence of a difference between the two groups in the primary or assisted patency rates at four years (13 grafts were patent from 15 PAA treatments in each group; RR 1.00, 95% CI 0.76 to 1.32; moderate-certainty evidence); the effects were imprecise and compatible with the benefit of either endovascular stent graft or surgery or no difference. Mean hospital stay was shorter in the endovascular group (4.3 days for the endovascular group versus 7.7 days for the surgical group; mean difference (MD) -3.40 days, 95% CI -4.42 to -2.38; P < 0.001; moderate-certainty evidence). Mean operating time was also reduced in the endovascular group (75.4 minutes in the endovascular group versus 195.3 minutes in the surgical group; MD -119.90 minutes, 95% CI -137.71 to -102.09; P < 0.001; moderate-certainty evidence). Limb salvage was 100% in both groups. Data on local wound complications were not published in the trial report.

AUTHORS' CONCLUSIONS

Evidence to determine the effectiveness of endovascular stent graft versus conventional open surgery for the treatment of asymptomatic PAAs is limited to data from one small study. At one year there is moderate-certainty evidence that primary patency may be improved in the surgery group but assisted primary patency rates were similar between groups. At four years there was no clear benefit from either endovascular stent graft or surgery to primary or assisted primary patency (moderate-certainty evidence). As both operating time and hospital stay were reduced in the endovascular group (moderate-certainty evidence), it may represent a viable alternative to open repair of PAA. A large multicenter RCT may provide more information in the future. However, difficulties in recruiting enough patients are likely, unless it is an international collaboration including a number of high volume vascular centres.

In Vivo Morphological Changes of the Femoropopliteal Arteries due to Knee Flexion After Endovascular Treatment of Popliteal Aneurysm

Purpose: To evaluate morphological changes of the femoropopliteal (FP) arteries due to limb flexion in patients undergoing endovascular treatment of popliteal artery aneurysms (PAAs). Materials and Methods: Seven male patients (mean age 68 years) underwent endovascular treatment of PAA with a Viabahn stent-graft between January 2013 and December 2017. During follow-up, one contrast-enhanced computed tomography angiography (CTA) scan of the lower limbs was acquired for each recruited patient. A standardized CTA protocol for acquisitions in both straight-leg and bent-leg positions was used to visualize changes in artery shape due to limb flexion. Three-dimensional reconstruction of the FP segment was performed to compute mean diameter and eccentricity of the vascular lumen and to measure length, tortuosity, and curvature of the vessel centerline in 3 arterial zones: (A) between the origin of the superficial femoral artery and the proximal end of the stent-graft, (B) within the stent-graft, and (C) from the distal end of the stent-graft to the origin of the anterior tibial artery. Results: After limb flexion, all zones of the FP segment foreshortened: 6% in zone A (p=0.001), 4% in zone B (p=0.001), and 8% in zone C (p=0.07), which was the shortest (mean 4.5±3.6 cm compared with 23.8±5.7 cm in zone A and 23.6±7.4 cm in zone B). Tortuosity increased in zone A (mean 0.03 to 0.05, p=0.03), in zone B (0.06 to 0.15, p=0.005), and in zone C (0.027 to 0.031, p=0.1). Mean curvature increased 15% (p=0.05) in zone A, 27% (p=0.005) in zone B, and 95% (p=0.06) in zone C. In all zones, the mean artery diameter and eccentricity were not significantly affected by limb flexion. Conclusion: Limb flexion induces vessel foreshortening and increases mean curvature and tortuosity of the FP segment both within and outside the area of the stent-graft.

Benefits and harms of screening men for abdominal aortic aneurysm in Sweden: a registry-based cohort study

BACKGROUND

Large reductions in the incidence of abdominal aortic aneurysm (AAA) and AAA-related mortality mean that results from randomised trials of screening for the disorder might be out-dated. The aim of this study was to estimate the effect of AAA screening in Sweden on disease-specific mortality, incidence, and surgery.

METHODS

Individual data on the incidence of AAA, AAA mortality, and surgery for AAA in a cohort of men aged 65 years who were invited to screening between 2006 and 2009, were compared with data from an age-matched contemporaneous cohort of men who were not invited for AAA screening. We also analysed national data for all men aged 40-99 years between Jan 1, 1987, and Dec 31, 2015, to explore background trends. Adjustment for confounding was done by weighting the analyses with a propensity score obtained from a logistic regression model on cohort year, marital status, educational level, income, and whether the patient already had an AAA diagnosis at baseline. Adjustment for differential attrition was also done by weighting the analyses with the inverse probability of still being in the cohort 6 years after screening. Generalised estimating equations were used to adjust the variance for repeated measurement and in response to the weighting.

FINDINGS

AAA mortality in Swedish men has decreased from 36 to ten deaths per 100 000 men aged 65-74 years between the early 2000s and 2015. Mortality decreased at similar rates in all Swedish counties, irrespective of whether AAA screening was offered. After 6 years with screening, we found a non-significant reduction in AAA mortality associated with screening (adjusted odds ratio [aOR] 0·76, 95% CI 0·38-1·51), which means that two men (95% CI -3 to 7) avoid death from AAA for every 10 000 men offered screening. Screening was associated with increased odds of AAA diagnosis (aOR 1·52, 95% CI 1·16-1·99; p=0·002) and an increased risk of elective surgery (aOR 1·59, 95% CI 1·20-2·10; p=0·001), such that for every 10 000 men offered screening, 49 men (95% CI 25-73) were likely to be overdiagnosed, 19 of whom (95% CI 1-37) had avoidable surgery that increased their risk of mortality and morbidity.

INTERPRETATION

AAA screening in Sweden did not contribute substantially to the large observed reductions in AAA mortality. The reductions were mostly caused by other factors, probably reduced smoking. The small benefit and substantially less favourable benefit-to-harm balance call the continued justification of the intervention into question.

FUNDING

Research Unit and Section for General Practice, FoUU-centrum Fyrbodal, Sweden, and the region of Västra Götaland, Sweden.