Predicting Prosthetic Mobility at Discharge From Rehabilitation Following Major Amputation in Vascular Surgery.

OBJECTIVE: This study aimed to construct a decision aid to estimate the likelihood of independence with a prosthesis following rehabilitation for limb loss secondary to advanced ischaemia (acute or chronic limb threatening ischaemia) or diabetic foot disease (DFD). A secondary aim was to determine whether prosthetic independence is a surrogate marker of long term survival. METHODS: A retrospective cohort study of a prospectively maintained database of unilateral amputations due to ischaemia or DFD entering rehabilitation between 2007 and 2020 was performed. Predictors of independent prosthetic mobility (IPM) were used in construction of the IPM prediction model, which underwent bootstrap internal and criterion validation through correlation with predictors of other measures of function: Timed Up and Go (TUG) and two minute walk test. Kaplan-Meier and Cox regression analyses were performed to address the secondary aim. RESULTS: Of the 771 patients included, only 49.9% of amputees achieved IPM. Independent negative predictors of IPM were age > 75 years, female sex, higher amputation level, active malignancy, cerebrovascular disease, end stage renal disease, and cognitive impairment. The model yielded high discrimination (C statistic 0.778), and internal validation was demonstrated with bootstrapping (C statistic 0.778), confirming no over optimism. There was a strong correlation between IPM, TUG, and two minute distance and their predictors, confirming strong criterion validity. The IPM group had a median survival of 93.7 (80.7, 105) months, whereas the non-IPM group fared worse with a median survival of 56.6 (48.5, 66.7) months (p < .001). CONCLUSION: An internally validated decision aid for estimating the likelihood of independence with a prosthesis after major amputation was constructed. A strong association between female sex and poorer prosthetic mobility was observed. Prosthetic function was shown to be a surrogate marker of long term survival. Future research will involve external validation studies to confirm the generalisability of the decision aid in clinical practice.

Association between statin-use and mobility and long-term survival after major lower limb amputation.

AIM: The aim of this study was to determine if there is an association between statin-use and prosthetic mobility and long-term survival in patients receiving rehabilitation after major amputation for lower limb arterial disease. METHODS: A retrospective analysis of prospectively maintained data (2008-2020) from a centre for rehabilitation was performed. Patients were grouped by statin-use status and sub-grouped by the combination of statin and antithrombotic drugs (antiplatelets or anticoagulants). Outcomes were prosthetic mobility (SIGAM score, timed-up-go and 2-min walking distance) and long-term survival. Regression, Kaplan-Meier and Cox-proportional hazard analyses were performed to test associations adjusted to confounders. RESULTS: Of 771 patients, 499 (64.7%) were on a statin before amputation or prescribed a statin peri-operatively. Rate of statin-use was significantly lower among female (53.3%) compared to male (68.2%) patients, P < 0.001. Statin-use was associated with significantly better prosthetic independence (53.1% vs 44.1%, P = 0.017), timed-up-go (mean difference of 4 s, P = 0.04) and long-term survival HR 0.59 (0.48-0.72, P < 0.001). Significance persisted after adjusting for confounding factors and in subgroup analyses. The combination of statin with antiplatelet was associated with the most superior survival, HR 0.51 (0.40-0.65, P < 0.001). Sensitivity analysis (exclusion of non-users of prosthesis) showed that statin-use remained a significant indicator of longer survival, maximally when combined with antiplatelet use HR 0.52 (0.39-0.68, P < 0.001). CONCLUSIONS: Statin-use is associated with better mobility and long-term survival in rehabilitees after limb loss, particularly when used in combination with antiplatelets. Significantly lower rates of statin-use were observed in female patients. Further research is warranted on gender disparities in statin-use and causality in their association with improved mobility and survival.

Migration and sac expansion as modes of midterm therapeutic failure after endovascular aneurysm sealing.

BACKGROUND: Endovascular aneurysm sealing (EVAS) is a disruptive technology to treat abdominal aortic aneurysm (AAA). The use of sac filling rather than endograft fixation was designed to treat aortic aneurysms in a wide range of morphologic appearances and to reduce endoleaks. There are few data reporting outcomes beyond postoperative follow-up. This study reports outcomes up to 5 years for Nellix (Endologix, Irvine, Calif) EVAS. METHODS: Data were prospectively collected for EVAS patients from the time of adoption of EVAS in 2013. All patients treated with the Nellix device are included in this study, and as such, it reports on infrarenal, ruptured, and iliac aneurysms as well as the Nellix-in-Nellix application. Juxtarenal and suprarenal aneurysms were treated using the EVAS system with parallel grafts into the visceral vessels and are included. Therapeutic failure, a composite outcome of migration, sac expansion >5 mm, type Ia and type Ib endoleak, and secondary aortic rupture, was the primary outcome along with all-cause mortality, aneurysm-related mortality, and reintervention rates. RESULTS: There were 295 EVAS cases undertaken between March 2013 and July 2018. Indications for treatment were infrarenal (n = 185), juxtarenal and suprarenal (n = 73), ruptured (n = 18), and iliac (n = 13) aneurysms. There were 15 reinterventions using the Nellix-in-Nellix application. In some cases, EVAS was used to salvage failing endovascular or open aneurysm repairs. Median follow-up was 2.42 years (interquartile range, 1.07-3.57 years). Therapeutic failure was observed in 98 of the 295 cases (33.2%) overall and exceeded 50% in some subgroups. In 71 cases (24.1%), reintervention was performed, with reasons for no reintervention being mainly physiologic. Complications leading to therapeutic failure were most commonly seen beyond 2 years of follow-up. There were 15 secondary ruptures (5.36%), and 9 EVAS devices required explantation either electively or for aortic rupture. CONCLUSIONS: EVAS with the Nellix device has not met expectations, and early encouraging results have been eroded. The incidence of therapeutic failure has been high, occurring 2 years and beyond after implantation. The Nellix system has been voluntarily recalled by Endologix, and the CE mark has subsequently been suspended. The adoption of EVAS as a disruptive technology highlights the need for cautious adoption of novel technologies and the strict governance around such arrangements.

Midterm results of endovascular aneurysm sealing to treat abdominal aortic aneurysm.

BACKGROUND: Endovascular aneurysm sealing (EVAS) represents a novel approach to the treatment of abdominal aortic aneurysms. It uses polymer technology to achieve an anatomic seal within the sac of the aneurysm. This cohort study reports the early clinical outcomes, technical refinements, and learning curve during the initial EVAS experience at a single institution. METHODS: Results from 150 consecutive EVAS cases for intact, infrarenal abdominal aortic aneurysms are reported here. These cases were undertaken between March 2013 and July 2015. Preoperative, perioperative, and postoperative data were collected for each patient prospectively. RESULTS: The median age of the cohort was 76.6 years (interquartile range, 70.2-80.9 years), and 87.3% were male. Median aneurysm diameter was 62.0 mm (IQR, 58.0-69.0 mm). Adverse neck morphology was seen in 69 (46.0%) patients, including aneurysm neck length <10 mm (17.3%), neck diameter >32 mm or <18 mm (8.7%), and neck angulation >60 degrees (15.3%). Median follow-up was 687 days (IQR, 463-897 days); 37 patients (24.7%) underwent reintervention. The rates of unresolved endoleak are 1.3% type IA, 0.7% type IB, and 2.7% type I. There were no type III endoleaks. There have been seven secondary ruptures in this cohort; all but one of these patients survived after reintervention. Only one rupture occurred in an aneurysm that had been treated within the manufacturer's instructions for use (IFU). CONCLUSIONS: The rate of unresolved endoleaks is satisfactorily low. The incidence of secondary rupture is of concern; however, when the IFU are adhered to, the rate is very low. The results of this study suggest that working within the IFU yields better clinical results.

Short Stay EVAR is Safe and Cost Effective.

OBJECTIVE: Reducing length of stay (LOS) following surgery offers the potential to improve resource utilisation. Endovascular aneurysm repair (EVAR) is now delivered with a low level of morbidity and as such may be deliverable as a "23 hour stay" intervention. This systematic review aims to assess safety, feasibility and cost effectiveness of a short stay EVAR pathway. METHODS: A database search of Ovid MEDLINE (1996 - April 2018) and Embase (1974 - April 2018) was completed. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. A Newcastle-Ottawa Scale was applied to assess study bias. RESULTS: In total, 570 papers were identified through the literature search, of which 32 abstracts were screened. This led to nine papers being assessed for eligibility. From five suitable studies, 450 (75%) patients were successfully discharged the same or next day after EVAR. Complications most often occurred within 3 hours of surgery, and major complications requiring intensive treatment unit admission occurred within 6 hours. Readmission rates were 0-5% for those discharged early, with no difference in 30 day readmission. Early discharge led to a statistically significant cost saving of £13,360 (LOS four days) to £9844 (LOS one day). CONCLUSION: Selected patients can safely undergo EVAR using a short stay pathway. A period of monitoring 6 h post-operatively for low risk patients would be sufficient. Reducing length of stay after EVAR in the UK from the current median of three days to 1.5 days would free 4361 bed days and lead to a saving of approximately £1,800,000 annually.

Feature selection through validation and un-censoring of endovascular repair survival data for predicting the risk of re-intervention.

BACKGROUND: Feature selection (FS) process is essential in the medical area as it reduces the effort and time needed for physicians to measure unnecessary features. Choosing useful variables is a difficult task with the presence of censoring which is the unique characteristic in survival analysis. Most survival FS methods depend on Cox's proportional hazard model; however, machine learning techniques (MLT) are preferred but not commonly used due to censoring. Techniques that have been proposed to adopt MLT to perform FS with survival data cannot be used with the high level of censoring. The researcher's previous publications proposed a technique to deal with the high level of censoring. It also used existing FS techniques to reduce dataset dimension. However, in this paper a new FS technique was proposed and combined with feature transformation and the proposed uncensoring approaches to select a reduced set of features and produce a stable predictive model. METHODS: In this paper, a FS technique based on artificial neural network (ANN) MLT is proposed to deal with highly censored Endovascular Aortic Repair (EVAR). Survival data EVAR datasets were collected during 2004 to 2010 from two vascular centers in order to produce a final stable model. They contain almost 91% of censored patients. The proposed approach used a wrapper FS method with ANN to select a reduced subset of features that predict the risk of EVAR re-intervention after 5 years to patients from two different centers located in the United Kingdom, to allow it to be potentially applied to cross-centers predictions. The proposed model is compared with the two popular FS techniques; Akaike and Bayesian information criteria (AIC, BIC) that are used with Cox's model. RESULTS: The final model outperforms other methods in distinguishing the high and low risk groups; as they both have concordance index and estimated AUC better than the Cox's model based on AIC, BIC, Lasso, and SCAD approaches. These models have p-values lower than 0.05, meaning that patients with different risk groups can be separated significantly and those who would need re-intervention can be correctly predicted. CONCLUSION: The proposed approach will save time and effort made by physicians to collect unnecessary variables. The final reduced model was able to predict the long-term risk of aortic complications after EVAR. This predictive model can help clinicians decide patients' future observation plan.

A systematic review and meta-analysis indicates underreporting of renal dysfunction following endovascular aneurysm repair.

Deterioration in renal function has been described after endovascular repair of abdominal aortic aneurysms (EVRs). The etiology is multifactorial and represents an important therapeutic target. A need exists to quantitatively summarize incidence and severity of renal dysfunction after EVR to allow better-informed attempts to preserve renal function and improve life expectancy. Here a systematic search was performed using Medline and Embase for renal function after EVR applying PRISMA statements. Univariate and multivariate random-effects meta-analyses were performed to estimate pooled postoperative changes in serum creatinine and creatinine clearance at four time points after EVR. Clinically relevant deterioration in renal function was also estimated at 1 year or more after EVR. Pooled probability of clinically relevant deterioration in renal function at 1 year or more was 18% (95% confidence interval of 14-23%, I2 of 82.5%). Serum creatinine increased after EVR by 0.05 mg/dl at 30 days/1 month, 0.09 mg/dl at 1 month to 1 year, and 0.11 mg/dl at 1 year or more (all significant). Creatinine clearance decreased after EVR by 5.65 ml/min at 1 month-1 year and by 6.58 ml/min at 1 year or more (both significant). Thus, renal dysfunction after EVR is common and merits attention.

A Systematic Review and Meta-analysis of Endovascular Popliteal Aneurysm Repair Using the Hemobahn/Viabahn Stent-Graft.

PURPOSE: To perform an evidence synthesis study to assess outcomes of endovascular repair of popliteal artery aneurysms (PAAs) using the Hemobahn or Viabahn stent-graft. METHODS: A systematic literature review was conducted conforming to established standards to identify articles published between 1996 (the date of introduction of the Hemobahn stent-graft) and 2013 reporting stent-graft repair of PAAs in at least 10 patients. The data were pooled for Kaplan-Meier analysis of primary and secondary patency rates [presented with 95% confidence intervals (CIs)] as the primary outcomes. Random effects meta-analysis was performed for secondary outcomes that included rates of reintervention, endoleak, stent-graft fracture, and limb salvage. RESULTS: Fourteen studies reported outcomes for 514 PAAs. There was considerable heterogeneity in reporting standards among studies. Pooled primary and secondary patency rates were 69.4% (95% CI 63.3% to 76.2%) and 77.4% (95% CI 70.1% to 85.3%), respectively, at 5 years. Five studies (including only one randomized controlled trial) compared surgical to endovascular repair; no difference was found in primary patency on evidence synthesis (hazard ratio 1.30, 95% CI 0.79 to 12.14, p=0.189). CONCLUSION: Stent-graft repair provides a feasible treatment option for anatomically suitable PAAs. Further studies are required to optimize both patient selection and follow-up protocols.

Appearance of the Nellix endovascular aneurysm sealing system on computed tomography: implications for postoperative imaging surveillance.

PURPOSE: To describe the imaging characteristics of the Nellix Endovascular Aneurysm Sealing (EVAS) System on serial computed tomography (CT) surveillance. METHODS: Sixty-eight patients undergoing EVAS were enrolled in a surveillance protocol that included CT scans prior to hospital discharge and at 3, 6, and 9 months postoperatively. Images were analyzed for the presence of gas within the endobag, endoleak, and for maximum radiodensity measured in Hounsfield units (HU) within the uppermost, middle, and lowermost regions of each endobag. RESULTS: Gas was seen within the endobags of all 68 EVAS repairs at the first postoperative CT compared with 2 (5.6%) of 36 undergoing the 3-month scan. The endobags appeared radiodense during initial imaging, and the median (interquartile range) radiodensity of the Nellix polymer decreased from 158.3 HU (149.5; 169.5) at the postoperative CT to 81.0 HU (74.0; 88.0) at 3 months, excluding 3 cases in which contrast pre-fill was utilized. Type I endoleak was seen at the periphery of the aneurysm sac or in the cleft between the endobags, with a substantially different appearance to endoleak after endovascular aneurysm repair. CONCLUSION: The evolution of CT appearances after EVAS was characteristic and predictable. The device endobags were initially radiodense, which may impact the detection of endoleak within 3 months of EVAS. Endoleaks after EVAS were seen in a different anatomical area to endoleaks after conventional stent-graft repair.

Endovascular aneurysm sealing for the treatment of ruptured abdominal aortic aneurysms.

PURPOSE: To assess the feasibility and report preliminary results of ruptured abdominal aortic aneurysm (rAAA) repair with endovascular aneurysm sealing (EVAS), a novel therapeutic alternative whose feasibility has not been established in rAAAs due to the unknown effects of the rupture site on the ability to achieve sealing. CASE REPORT: Between December 2013 and April 2014, 5 patients (median age 71 years, range 57-90; 3 men) with rAAAs were treated with the Nellix EVAS system at a single institution. Median aneurysm diameter was 70 mm (range 67-91). Aneurysm morphology in 4 of the 5 patients was noncompliant with instructions for use (IFU) for both EVAS and standard stent-grafts; the remaining patient was outside the IFU for standard stent-grafts but treated with EVAS under standard IFU for the Nellix system. Median Hardman index was 2 (range 0-3). Two patients died of multiorgan failure after re-laparotomy and intraoperative cardiac arrest, respectively. Among survivors, all devices were patent with no signs of endoleak or failed aneurysm sac sealing at 6 months (median follow-up 9.2 months). CONCLUSION: EVAS for the management of infrarenal rAAAs appears feasible. The use of EVAS in emergency repairs may broaden the selection criteria of the current endovascular strategy to include patients with more complex aneurysm morphology.