Patients living farther from a tertiary care center are more likely to undergo peripheral arterial bypass for acute and chronic limb-threatening ischemia.

OBJECTIVE: The aim of this study was to assess the association between the proximity to the tertiary care hospital and the severity of peripheral arterial disease (PAD) at the time of lower extremity bypass (LEB) in a rural-urban mix region. METHODS: Patients undergoing LEB from 2010 to 2020 at Penn State Milton S. Hershey Medical Center were reviewed and stratified into two study groups based on a median distance from hospital (ie, Group I: ≥34 miles and Group II: <34 miles). Patients' demographic features, preoperative data including comorbidities, and medications were analyzed. A univariate analysis for the patient characteristics between the two study groups, along with evaluation of postoperative outcomes, and a multivariate predictive modeling to study the PAD stage as the indication of LEB was performed. A P-value of < .05 was set as a significant difference between the groups for all the analyses. RESULTS: There were 175 patients (49.9%) in Group I and 176 patients (50.1%) in Group II with a mean age of 65 ± 11.92 years (median, 64.61 years). No significant difference was observed in gender (P = .530), age (P = .906), and functional status (P = .830) between study groups. It was observed that patients in Group I were more likely to be overweight or obese (71.3% vs 57%; P = .007) and had a prior history of myocardial infarction (24.3% vs 15.3%; P = .036) in comparison to Group II. No postoperative outcomes were found to be statistically different between the study groups. The multivariate analyses based on various confounders displayed that patients in Group I had 56% higher likelihood of LEB for chronic limb-threatening ischemia (adjusted odds ratio, 1.56; 95% confidence interval, 0.92-2.62; P = .042). Group I patients also had five times higher odds of LEB for acute limb ischemia (adjusted odds ratio, 5.07; 95% confidence interval, 1.42-18.13; P = .012) as compared with those in the Group II. CONCLUSIONS: Patients' proximity to a major tertiary hospital may have implications on the disease progression for patients with PAD and could also be related to inadequate vascular services in primary and secondary hospitals. Lack of preventive care and disease management in regions afar from a tertiary hospital could be other implicating factors and highlights the need for outreach programs, along with distribution of vascular specialists, to reduce geographical disparities and ensure equity in access to care.

Role of Hemodynamic Assessment and Limitations in Ankle-Brachial Pressure Index, Toe- Brachial Pressure Index to Predict Wound Healing After Revascularization.

Chronic limb-threatening ischemia (CLTI) represents one of the most severe forms of peripheral arterial disease implying impaired wound healing and tissue loss at the same time posing a significant impact on the quality of life of patients and a serious economic burden on healthcare systems around the world. A major challenge in the management of patients with CLTI is the validity and role of non-invasive hemodynamic parameters in assessing their clinical status before and after revascularization. Traditionally, the diagnosis of CLTI is routinely based on clinical symptoms and confirmed by measurements of non-invasive limb hemodynamics including ankle-brachial pressure index (ABPI) and toe-brachial pressure index (TBPI). However, whether these indices alone can provide definitive treatment or be used as adjunctive tool along with the implementation of novel techniques to help guide revascularization for CLI patients still remains unclear.

Impact of Intensity of Vascular Care Preceding Major Amputation Among Patients With Chronic Limb-Threatening Ischemia.

BACKGROUND: Lower-limb amputation rates in patients with chronic limb-threatening ischemia vary across the United States, with marked disparities in amputation rates by gender, race, and income status. We evaluated the association of patient, hospital, and geographic characteristics with the intensity of vascular care received the year before a major lower-limb amputation and how intensity of care associates with outcomes after amputation. METHODS: Using Medicare claims data (2016-2019), beneficiaries diagnosed with chronic limb-threatening ischemia who underwent a major lower-limb amputation were identified. We examined patient, hospital, and geographic characteristics associated with the intensity of vascular care received the year before amputation. Secondary objectives evaluated all-cause mortality and adverse events following amputation. RESULTS: Of 33 036 total Medicare beneficiaries undergoing major amputation, 7885 (23.9%) were due to chronic limb-threatening ischemia; of these, 4988 (63.3%) received low-intensity and 2897 (36.7%) received high-intensity vascular care. Mean age, 76.6 years; women, 38.9%; Black adults, 24.5%; and of low income, 35.2%. After multivariable adjustment, those of low income (odds ratio, 0.65 [95% CI, 0.58-0.72]; P<0.001), and to a lesser extent, men (odds ratio, 0.89 [95% CI, 0.81-0.98]; P=0.019), and those who received care at a safety-net hospital (odds ratio, 0.87 [95% CI, 0.78-0.97]; P=0.012) were most likely to receive low intensity of care before amputation. High-intensity care was associated with a lower risk of all-cause mortality 2 years following amputation (hazard ratio, 0.79 [95% CI, 0.74-0.85]; P<0.001). CONCLUSIONS: Patients who were of low-income status, and to a lesser extent, men, or those cared for at safety-net hospitals were most likely to receive low-intensity vascular care. Low-intensity care was associated with worse long-term event-free survival. These data emphasize the continued disparities that exist in contemporary vascular practice.

Early peripheral vascular interventions for claudication are associated with higher rates of late interventions and progression to chronic limb threatening ischemia.

OBJECTIVE: Despite societal guidelines that peripheral vascular intervention (PVI) should not be the first-line therapy for intermittent claudication, a significant number of patients will undergo PVI for claudication within 6 months of diagnosis. The aim of the present study was to investigate the association of early PVI for claudication with subsequent interventions. METHODS: We evaluated 100% of Medicare fee-for-service claims to identify all beneficiaries with a new diagnosis of claudication from January 1, 2015 to December 31, 2017. The primary outcome was late intervention, defined as any femoropopliteal PVI performed >6 months after the claudication diagnosis (through June 30, 2021). Kaplan-Meier curves were used to compare the cumulative incidence of late PVI for claudication patients with early (≤6 months) PVI vs those without early PVI. A hierarchical Cox proportional hazards model was used to evaluate the patient- and physician-level characteristics associated with late PVIs. RESULTS: A total of 187,442 patients had a new diagnosis of claudication during the study period, of whom 6069 (3.2%) had undergone early PVI. After a median follow-up of 4.39 years (interquartile range, 3.62-5.17 years), 22.5% of the early PVI patients had undergone late PVI vs 3.6% of those without early PVI (P < .001). Patients treated by high use physicians of early PVI (≥2 standard deviations; physician outliers) were more likely to have received late PVI than were patients treated by standard use physician of early PVI (9.8% vs 3.9%; P < .001). Patients who had undergone early PVI (16.4% vs 7.8%) and patients treated by outlier physicians (9.7% vs 8.0%) were more likely to have developed CLTI (P < .001 for both). After adjustment, the patient factors associated with late PVI included receipt of early PVI (adjusted hazard ratio [aHR], 6.89; 95% confidence interval [CI], 6.42-7.40) and Black race (vs White; aHR, 1.19; 95% CI, 1.10-1.30). The only physician factor associated with late PVI was a majority of practice in an ambulatory surgery center or office-based laboratory, with an increasing proportion of ambulatory surgery center or office-based laboratory services associated with significantly increased rates of late PVI (quartile 4 vs quartile 1; aHR, 1.57; 95% CI, 1.41-1.75). CONCLUSIONS: Early PVI after the diagnosis of claudication was associated with higher late PVI rates compared with early nonoperative management. High use physicians of early PVI for claudication performed more late PVIs than did their peers, especially those primarily delivering care in high reimbursement settings. The appropriateness of early PVI for claudication needs critical evaluation, as do the incentives surrounding the delivery of these interventions in ambulatory intervention suites.

Assessment of Parafoveal Diabetic Macular Ischemia on Optical Coherence Tomography Angiography Images to Predict Diabetic Retinal Disease Progression and Visual Acuity Deterioration.

Importance: The presence of diabetic macular ischemia (DMI) on optical coherence tomography angiography (OCTA) images predicts diabetic retinal disease progression and visual acuity (VA) deterioration, suggesting an OCTA-based DMI evaluation can further enhance diabetic retinopathy (DR) management. Objective: To investigate whether an automated binary DMI algorithm using OCTA images provides prognostic value on DR progression, diabetic macular edema (DME) development, and VA deterioration in a cohort of patients with diabetes. Design, Setting, and Participants: In this cohort study, DMI assessment of superficial capillary plexus and deep capillary plexus OCTA images was performed by a previously developed deep learning algorithm. The presence of DMI was defined as images exhibiting disruption of fovea avascular zone with or without additional areas of capillary loss, while absence of DMI was defined as images presented with intact fovea avascular zone outline and normal distribution of vasculature. Patients with diabetes were recruited starting in July 2015 and were followed up for at least 4 years. Cox proportional hazards models were used to evaluate the association of the presence of DMI with DR progression, DME development, and VA deterioration. Analysis took place between June and December 2022. Main Outcomes and Measures: DR progression, DME development, and VA deterioration. Results: A total of 321 eyes from 178 patients were included for analysis (85 [47.75%] female; mean [SD] age, 63.39 [11.04] years). Over a median (IQR) follow-up of 50.41 (48.16-56.48) months, 105 eyes (32.71%) had DR progression, 33 eyes (10.28%) developed DME, and 68 eyes (21.18%) had VA deterioration. Presence of superficial capillary plexus-DMI (hazard ratio [HR], 2.69; 95% CI, 1.64-4.43; P < .001) and deep capillary plexus-DMI (HR, 3.21; 95% CI, 1.94-5.30; P < .001) at baseline were significantly associated with DR progression, whereas presence of deep capillary plexus-DMI was also associated with DME development (HR, 4.60; 95% CI, 1.15-8.20; P = .003) and VA deterioration (HR, 2.12; 95% CI, 1.01-5.22; P = .04) after adjusting for age, duration of diabetes, fasting glucose, glycated hemoglobin, mean arterial blood pressure, DR severity, ganglion cell-inner plexiform layer thickness, axial length, and smoking at baseline. Conclusions and Relevance: In this study, the presence of DMI on OCTA images demonstrates prognostic value for DR progression, DME development, and VA deterioration.

Comparison of lower extremity bypass and peripheral vascular intervention for chronic limb-threatening ischemia in the Medicare-linked Vascular Quality Initiative.

OBJECTIVE: There is a relative lack of comparative effectiveness research on revascularization for patients with chronic limb-threatening ischemia (CLTI). We examined the association between lower extremity bypass (LEB) vs peripheral vascular intervention (PVI) for CLTI and 30-day and 5-year all-cause mortality and 30-day and 5-year amputation. METHODS: Patients undergoing LEB and PVI of the below-the-knee popliteal and infrapopliteal arteries between 2014 and 2019 were queried from the Vascular Quality Initiative, and outcomes data were obtained from the Medicare claims-linked Vascular Implant Surveillance and Interventional Outcomes Network database. Propensity scores were calculated on 15 variables using a logistic regression model to control for imbalances between treatment groups. A 1:1 matching method was used. Kaplan-Meier survival curves and hierarchical Cox proportional hazards regression with a random intercept for site and operator nested in site to account for clustered data compared 30-day and 5-year all-cause mortality between groups. Thirty-day and 5-year amputation were subsequently compared using competing risk analysis to account for the competing risk of death. RESULTS: There was a total of 2075 patients in each group. The overall mean age was 71 ± 11 years, 69% were male, and 76% were white, 18% were black, and 6% were of Hispanic ethnicity. Baseline clinical and demographic characteristics in the matched cohort were balanced between groups. There was no association between all-cause mortality over 30 days and LEB vs PVI (cumulative incidence, 2.3% vs 2.3% by Kaplan Meier; log-rank P-value = .906; hazard ratio [HR], 0.95; 95% confidence interval [CI], 0.62-1.44; P-value = .80). All-cause mortality over 5 years was lower for LEB vs PVI (cumulative incidence, 55.9% vs 60.1% by Kaplan Meier; log-rank P-value < .001; HR, 0.77; 95% CI, 0.70-0.86; P-value < .001). Accounting for competing risk of death, amputation over 30 days was also lower in LEB vs PVI (cumulative incidence function, 1.9% vs 3.0%; Fine and Gray P-value = .025; subHR, 0.63; 95% CI, 0.42-0.95; P-value = .025). There was no association between amputation over 5 years and LEB vs PVI (cumulative incidence function, 22.6% vs 23.4%; Fine and Gray P-value = .184; subHR, 0.91; 95% CI, 0.79-1.05; P-value = .184). CONCLUSIONS: In the Vascular Quality Initiative-linked Medicare registry, LEB vs PVI for CLTI was associated with a lower risk of 30-day amputation and 5-year all-cause mortality. These results will serve as a foundation to validate recently published randomized controlled trial data, and to broaden the comparative effectiveness evidence base for CLTI.

Poor utilization of palliative care among Medicare patients with chronic limb-threatening ischemia.

OBJECTIVE: Patients with chronic limb-threatening ischemia (CLTI) experience high annual mortality and would benefit from timely palliative care intervention. We sought to better characterize use of palliative care among patients with CLTI in the Medicare population. METHODS: Using Medicare data from 2017 to 2018, we identified patients with CLTI, defined as two or more encounters with a CLTI diagnosis code. Palliative care evaluations were identified using ICD-10-CM Z51.5 "Encounter for palliative care." Time intervals between CLTI diagnosis, palliative consultation, and death or end of follow-up were calculated. Associations between patient demographics, comorbidities, and palliative care consultation were assessed. RESULTS: A total of 12,133 Medicare enrollees with complete data were categorized as having CLTI. Of these, 7.4% (894) underwent a palliative care evaluation at a median of 170 days (interquartile range, 45-352 days) from their CLTI diagnosis. Compared with those who did not undergo evaluation, palliative patients were more likely to be dual eligible for Medicaid (45.2% vs 38.1%; P < .001) and had more comorbid conditions (P < .001). After controlling for gender and race, age (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.02-1.04), dual eligibility (OR, 1.40; 95% CI, 1.22-1.62), solid organ malignancy (OR, 2.82; 95% CI, 1.92-4.14), hematologic malignancy (OR, 2.24; 95% CI, 1.27-3.98), congestive heart failure (OR, 1.44; 95% CI, 1.15-1.88), complicated diabetes (OR, 1.35; 95% CI, 1.11-1.65), dementia (OR, 1.32; 95% CI, 1.04-1.66), and severe renal failure (OR, 1.56; 85% CI. 1.24-1.98) were independently associated with palliative care evaluation. During mean follow up of 410 ± 220 days, 16.9% (2044) of patients died at a mean of 268 (±189) days after their CLTI diagnosis. Among living patients, only 3.2% (325) underwent palliative evaluation. Comparatively, 27.8% (569) of patients who died received palliative care at a median of 196 days (interquartile range, 55-362 days) after their diagnosis and 15 days (interquartile range, 5-63 days) prior to death. CONCLUSIONS: Despite high mortality, palliative care services were rarely provided to Medicare patients with CLTI. Age, medical complexity, and income status may play a role in the decision to consult palliative care. When obtained, evaluations occurred closer to time of death than to time of CLTI diagnosis, suggesting misuse of palliative care as end-of-life care.

Updated estimates for the burden of chronic limb-threatening ischemia in the Medicare population.

OBJECTIVE: Estimates of chronic limb-threatening ischemia (CLTI) based on diagnosis codes of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) suggest a prevalence of 0.23%-0.32% and incidence of 0.20%-0.26% among Medicare patients. ICD-10-CM includes 144 CLTI diagnosis codes, allowing improved specificity in identifying affected patients. We sought to use ICD-10-CM diagnosis codes to determine the prevalence of CLTI among Medicare patients and describe the patient cohort affected by this condition. METHODS: Using two years of data from Centers for Medicare and Medicaid Services, we identified all patients that had at least one CLTI diagnosis code to determine prevalence and incidence rates. Sensitivity analyses were performed to compare our methodology to prior publications and quantify the extent of missed diagnoses. The number and type of vascular procedures that occurred after diagnosis were tabulated. A cohort of patients with two or more CLTI diagnosis codes were then identified for further descriptive analysis. Associations between patient demographics and survival were analyzed using Cox proportional hazards models. RESULTS: Over 65 million patients were enrolled in Medicare in 2017 to 2018. Of these, 480,227 had diagnosis of CLTI, with a corresponding to a 1-year incidence of 0.33% and a 2-year prevalence of 0.74%. Patients underwent an average of 43.6 vascular procedures per 100 person-years. Sensitivity analyses identified 89,805 additional patients that had a diagnosis code of peripheral arterial disease who underwent revascularization or amputation. Patients with CLTI were predominantly male (56.2%), white (76.4%), and qualified for Medicare due to age (64.0%). Thirty-seven percent were dual-eligible. One-year survival was 77.7%, significantly lower than estimated actuarial survival adjusted for age, sex, and race (95.1%; P < .001). Cox proportional hazards models demonstrate significantly increased mortality for men vs women (hazard ratio, 1.07; 95% confidence interval, 1.04-1.10; P < .001), but no association between race and overall survival (hazard ratio, 0.99; 95% confidence interval, 0.98-1.01; P = .83). CONCLUSIONS: Using ICD-10-CM diagnosis codes, we demonstrated slightly higher incidence and prevalence of CLTI than in published literature, reflecting our more complete methodology. Sensitivity analyses suggest that increased complexity of the highly specific ICD-10-CM coding may diminish capture of CLTI. Inclusion of patients with non-CLTI peripheral arterial disease diagnoses produces moderate increases in incidence and prevalence at the cost of decreased specificity in identifying patients with CLTI. Medicare patients with CLTI are older, and more commonly male, black, and dual eligible compared with the general Medicare population. Observed mid-term survival for patients with CLTI is significantly lower than actuarial estimates, confirming the importance of focused efforts on identifying and aligning goals of care in this complex patient population.

Cost-utility analysis of early versus delayed endovascular intervention in critical limb-threatening ischemia patients with rest pain.

OBJECTIVE: The prevalence of chronic limb-threatening ischemia (CLTI) and poor health outcomes are high in Germany. Serious consequences of CLTI such as amputation and mortality can be effectively prevented by the early use of evidence-based therapeutic measures such as endovascular intervention. We have developed a cost-utility analysis to compare endovascular intervention with bare metal stents (BMSs) and endovascular intervention after conservative treatment from the German payer perspective. METHODS: A Markov model, with a 5-year time horizon and seven states, was developed: (1) intervention, (2) stable 1, (3) major amputation, (4) reintervention, (5) stable 2, (6) care, and (7) all-cause death. Transition probabilities were obtained by pooling the outcomes from multiple clinical studies. The costs were estimated using data from the German diagnosis-related group system, the German rehabilitation fund, and related literature. Health-state utilities were obtained from the reported data. The primary outcomes were the quality-adjusted life-years (QALYs) and costs. RESULTS: Early BMS intervention after 5 years resulted in a cost of €23,913 and an increase of 2.5 QALYs per patient, and endovascular intervention with BMS after conservative treatment after 5 years resulted in a cost of €18,323 and an increase of 2 QALYs per patient. The incremental cost-effectiveness ratio was €12,438. The number of major amputations was reduced by 6%. The results of the structural, deterministic, and probabilistic sensitivity analyses were robust. CONCLUSIONS: Early endovascular intervention with BMS resulted in more QALYs and a reduced risk of major amputation for early-stage CLTI patients. Our results showed that early endovascular intervention is very cost-effective according to World Health Organization recommended cost-effectiveness thresholds. However, the clinical decision regarding the use of early endovascular intervention should be determined by individual patient-level eligibility and the physician's judgment.

A Systematic Review of Cost-Utility Analyses in Chronic Limb-Threatening Ischemia.

BACKGROUND: To review and describe the available literature on cost-utility analysis of revascularization and non-revascularization treatment approaches in chronic limb-threatening ischemia. METHODS: A systematic review was performed on cost-utility analysis studies evaluating revascularization (open surgery or endovascular), major lower extremity amputation, or conservative management in adult chronic limb-threatening ischemia patients. Six bibliographic databases and online registries were searched for English language articles up to August 2021. The outcome for cost-utility analysis was quality-adjusted in life years. Procedures were compared using incremental cost-effectiveness ratios which were converted to 2021 United States dollars. Study reporting quality was assessed using the 2022 Consolidated Health Economic Evaluation Reporting Standards statement. The study was registered in International Prospective Register of Systematic Reviews (CRD42021273602). RESULTS: Three trial-based and five model-based studies were included for review. Studies met between 14/28 and 20/28 criteria of the Consolidated Health Economic Evaluation Reporting Standards CHEERS statement. Only one study was written according to standardized reporting guidelines. Most studies evaluated infrainguinal disease, and adopted a health care provider perspective. There was a large variation in the incremental cost-effectiveness ratios presented across studies. Open surgical revascularization (incremental cost-effectiveness ratios: $3,678, $58,828, and $72,937), endovascular revascularization (incremental cost-effectiveness ratios: $52,036, $125,329, and $149,123), and mixed open or endovascular revascularization (incremental cost-effectiveness ratio: $8,094) maybe more cost-effective than conservative management. CONCLUSIONS: The application of cost-utility analyses in chronic limb-threatening ischemia is in its infancy. Revascularization in infrainguinal disease may be favored over major lower extremity amputation or conservative management. However, data is inadequate to support recommendations for a specific treatment. This review identifies short and long-term considerations to address the current state of evidence. Cost-utility analysis is an important tool in healthcare policy and should be encouraged amongst the vascular surgical community.

Small intestinal viability assessment using dielectric relaxation spectroscopy and deep learning.

Intestinal ischemia is a serious condition where the surgeon often has to make important but difficult decisions regarding resections and resection margins. Previous studies have shown that 3 h (hours) of warm full ischemia of the small bowel followed by reperfusion appears to be the upper limit for viability in the porcine mesenteric ischemia model. However, the critical transition between 3 to 4 h of ischemic injury can be nearly impossible to distinguish intraoperatively based on standard clinical methods. In this study, permittivity data from porcine intestine was used to analyze the characteristics of various degrees of ischemia/reperfusion injury. Our results show that dielectric relaxation spectroscopy can be used to assess intestinal viability. The dielectric constant and conductivity showed clear differences between healthy, ischemic and reperfused intestinal segments. This indicates that dielectric parameters can be used to characterize different intestinal conditions. In addition, machine learning models were employed to classify viable and non-viable segments based on frequency dependent dielectric properties of the intestinal tissue, providing a method for fast and accurate intraoperative surgical decision-making. An average classification accuracy of 98.7% was obtained using only permittivity data measured during ischemia, and 96.2% was obtained with data measured during reperfusion. The proposed approach allows the surgeon to get accurate evaluation from the trained machine learning model by performing one single measurement on an intestinal segment where the viability state is questionable.

Contemporary outcomes of limb-salvage procedures using Vascular Quality Initiative-Medicare-linked data: Racial and ethnic disparities persist.

BACKGROUND: Several reports have shown that ethnic and racial minority patients with chronic limb-threatening ischemia (CLTI) are more likely to undergo major amputation. Whether this disparity is driven by limited access to care, statistical discrimination, or biologic factors has remained a matter of debate. We studied the effects of race and ethnicity on the short- and long-term outcomes of limb-salvage procedures among patients with new-onset CLTI. METHODS: We identified all patients who had undergone first time (open or endovascular) revascularization for CLTI between January 2010 and December 2016 in the Vascular Quality Initiative-Medicare-linked database. These patients were divided into two groups: non-Hispanic White (NHW) and racial and ethnic minority (REM). The early end points included length of stay and operative mortality. The 2-year outcomes included major amputation, freedom from subsequent revascularization, number of limb salvage reinterventions, and all-cause mortality. Subanalyses comparing NHW and Hispanic patients and NHW and Black patients were also performed. RESULTS: Of 16,249 patients presenting with CLTI, 73.9% were NHW. The REM patients were younger (mean age, 69.9 ± 11.3 years vs 74.2 ± 10.5 years; P < .001) and more likely to be women (45.9% vs 37.7%; P < .001). Other baseline differences included a higher rate of smoking history, coronary artery disease, chronic obstructive pulmonary disease, and chronic kidney disease for the NHW group. In contrast, the REM patients were more likely to have diabetes and hypertension and were more likely to present with tissue loss (78% vs 76.6%; P = .04). The preoperative ankle brachial index and procedure type (endovascular vs open) were similar between the two groups. On multivariable analysis, the NHW group had had a 13% increase in the length of stay and a 25% decrease in operative mortality. Of the 2-year outcomes, the limb salvage estimate was 86% for the NHW group and 77.1% for the REM group (P < .001). A comparison between the two groups showed similar rates of freedom from subsequent revascularization (67.9% vs 67.1%; P =.2). The REM patients had had higher rates of overall survival (70.3% vs 68.4%; P = .01) compared with their NHW counterparts. The patients in the REM group were also more likely to have undergone more than two limb salvage reinterventions during follow-up (14.2% vs 8.6%; P < .001). After adjusting for potential confounders, the REM patients had significantly greater odds of major amputation at 2 years (adjusted hazard ratio, 1.49; 95% confidence interval, 1.36-1.63; P < .001). CONCLUSIONS: The results from the present Vascular Quality Initiative-Medicare-matched study have shown that REM patients continue to face a higher major amputation risk despite equivalent attempts at limb salvage. Further studies to identify the risk factors and evaluate intervention strategies that might be more effective in preventing amputation in this particular population are warranted.

Effect of postoperative antithrombotic therapy on lower extremity outcomes after infrapopliteal bypass for chronic limb-threatening ischemia.

OBJECTIVE: Although the current guidelines have recommended single antiplatelet therapy (SAPT) for patients undergoing revascularization for chronic limb-threatening ischemia (CLTI), antithrombotic management has varied by patient and provider. Our aim was to examine the effects of different postoperative antithrombotic regimens on 3-year clinical outcomes after infrapopliteal bypass for CLTI. METHODS: We identified patients who had undergone infrapopliteal bypass for CLTI in the Vascular Quality Initiative (VQI) registry from 2003 to 2017 with linkage to Medicare claims for long-term outcomes. We divided the patients into three cohorts according to the discharge antithrombotic regimen: SAPT (aspirin or clopidogrel), dual antiplatelet therapy (DAPT; aspirin and clopidogrel), or anticoagulation (AC) plus any antiplatelet (AP) agent. To reduce selection bias, we restricted the analysis cohorts to patients treated by providers who discharged >50% of patients with each antithrombotic regimen. Our primary outcome was 3-year major adverse limb events (MALE; major amputation or reintervention). The secondary outcomes included 3-year major amputation, reintervention, and mortality. We used Kaplan-Meier and Cox regression analyses to assess these outcomes stratified by antithrombotic regimen and adjusted for demographic, comorbid, clinical, and operative differences between the treatment groups with clustering at the center level. RESULTS: Among 1812 patients (median follow-up, >2 years), 693 (38%) were discharged with SAPT, 544 (30%) with DAPT, and 575 (32%) with AC+AP. At 3 years, the MALE rates were 75% with DAPT, 74% with AC+AP, and 68% with SAPT. In adjusted analyses with SAPT as the reference group, no differences were found in 3-year MALE with DAPT (adjusted hazard ratio [aHR], 1.0; 95% confidence interval [CI], 0.85-1.3; P = .71) or AC+AP (aHR, 1.1; 95% CI, 0.96-1.3; P = .14). Across the treatment groups, we also found no differences in the individual end points of 3-year major amputation (DAPT: aHR, 0.98; 95% CI, 0.72-1.3; AC+AP: aHR, 1.3; 95% CI, 0.96-1.7), reintervention (DAPT: aHR, 1.0; 95% CI, 0.84-1.3; AC+AP: aHR, 1.1; 95% CI, 0.96-1.3), or mortality (DAPT: aHR, 1.1; 95% CI, 0.88-1.4; AC+AP: aHR, 0.95; 95% CI, 0.74-1.2). In a sensitivity analysis evaluating patients treated by providers who discharged >60%, >70%, or >80% of patients with these regimens, the association between antithrombotic regimen and MALE was unchanged. CONCLUSIONS: Compared with SAPT, DAPT and anticoagulation therapy were not associated with improved outcomes among Medicare beneficiaries who had undergone infrapopliteal bypass for CLTI at VQI participating centers. These findings support current guidelines recommending SAPT after lower extremity bypass and suggest that the routine use of DAPT or anticoagulation therapy might not provide clinical benefit in this high-risk, elderly population. However, further evaluation of the risks and benefits of various antithrombotic regimens in relevant subgroups is warranted.

Peripheral Arterial Disease Located in the Feet of Patients With Diabetes and Foot Ulceration Demands a New Approach to the Assessment of Ischemia.

Peripheral arterial disease (PAD) is common below the knee in diabetes but arteries in the foot are controversially said to be spared of occlusive disease. This is relevant to the convenient site of vascular assessment that is recommended in guidelines. Should assessment be distal at toe/forefoot to detect foot disease or only proximal to detect disease at ankle level? The objective was to determine frequency of PAD at foot and ankle level. This was a cross-sectional observational study, evaluating arterial disease proximally by palpation of pedal pulses and Ankle Brachial Index (ABI), and distally by Toe Brachial Index (TBI), and forefoot transcutaneous oxygen tension (tcpO2), in consecutive patients presenting with foot ulceration. We assessed 301 limbs in 154 patients: 59% of limbs were ulcerated. PAD in the foot was detected in 70% and 74% of limbs by TBI and forefoot tcpO2, respectively, but PAD at ankle level only in 51% and 34% by pulse palpation and ABI, respectively. In limbs with "normal" ABI, PAD was present in the foot in 70% as indicated by low TBI, and in 73% by low tcpO2, with 70% to 64% having associated ulceration, respectively. When compared with arterial waveforms, as a measure of PAD, TBI gave an excellent AUC (area under the curve of the receiver operating characteristic curve) of 0.81 (95% confidence interval: 0.73-0.89), but ABI gave a poor AUC of 0.65 (95% confidence interval: 0.55-0.76). In conclusion, arterial disease is important in the foot and can be detected by TBI, which should be performed even when ABI is normal. Guidelines that recommend TBI only if ABI is artificially raised need updating.

A MULTITASK DEEP-LEARNING SYSTEM FOR ASSESSMENT OF DIABETIC MACULAR ISCHEMIA ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IMAGES.

PURPOSE: We aimed to develop and test a deep-learning system to perform image quality and diabetic macular ischemia (DMI) assessment on optical coherence tomography angiography (OCTA) images. METHODS: This study included 7,194 OCTA images with diabetes mellitus for training and primary validation and 960 images from three independent data sets for external testing. A trinary classification for image quality assessment and the presence or absence of DMI for DMI assessment were labeled on all OCTA images. Two DenseNet-161 models were built for both tasks for OCTA images of superficial and deep capillary plexuses, respectively. External testing was performed on three unseen data sets in which one data set using the same model of OCTA device as of the primary data set and two data sets using another brand of OCTA device. We assessed the performance by using the area under the receiver operating characteristic curves with sensitivities, specificities, and accuracies and the area under the precision-recall curves with precision. RESULTS: For the image quality assessment, analyses for gradability and measurability assessment were performed. Our deep-learning system achieved the area under the receiver operating characteristic curves >0.948 and area under the precision-recall curves >0.866 for the gradability assessment, area under the receiver operating characteristic curves >0.960 and area under the precision-recall curves >0.822 for the measurability assessment, and area under the receiver operating characteristic curves >0.939 and area under the precision-recall curves >0.899 for the DMI assessment across three external validation data sets. Grad-CAM demonstrated the capability of our deep-learning system paying attention to regions related to DMI identification. CONCLUSION: Our proposed multitask deep-learning system might facilitate the development of a simplified assessment of DMI on OCTA images among individuals with diabetes mellitus at high risk for visual loss.

Assessment of Detailed Photoreceptor Structure and Retinal Sensitivity in Diabetic Macular Ischemia Using Adaptive Optics-OCT and Microperimetry.

Purpose: The purpose of this study was to assess density and morphology of cone photoreceptors (PRs) and corresponding retinal sensitivity in ischemic compared to nonischemic retinal capillary areas of diabetic eyes using adaptive optics optical coherence tomography (AO-OCT) and microperimetry (MP). Methods: In this cross-sectional, observational study five eyes of four patients (2 eyes with proliferative diabetic retinopathy (DR) and 3 eyes moderate nonproliferative DR) were included. PR morphology and density was manually assessed in AO-OCT en face images both at the axial position of the inner-segment outer segment (IS/OS) and cone outer segment tips (COSTs). Retinal sensitivity was determined by fundus-controlled microperimetry in corresponding areas (MP-3, Nidek). Results: In AO-OCT, areas affected by capillary nonperfusion showed severe alterations of cone PR morphology at IS/OS and COST compared to areas with intact capillary perfusion (84% and 87% vs. 9% and 8% of area affected for IS/OS and COST, respectively). Mean reduction of PR signal density in affected areas compared to those with intact superficial capillary plexus (SCP) and deep capillary plexus (DCP) perfusion of similar eccentricity was -38% at the level of IS/OS (P = 0.01) and -39% at the level of COST (P = 0.01). Mean retinal sensitivity was 10.8 ± 5.4 in areas affected by DCP nonperfusion and 28.2 ± 1.5 outside these areas (P < 0.001). Conclusions: Cone PR morphology and signal density are severely altered in areas of capillary nonperfusion. These structural changes are accompanied by a severe reduction of retinal sensitivity, indicating the importance of preventing impaired capillary circulation in patients with DR.

A health insurance claims analysis on the effect of female sex on long-term outcomes after peripheral endovascular interventions for symptomatic peripheral arterial occlusive disease.

OBJECTIVE: Several reports have addressed sex disparities in peripheral arterial occlusive disease (PAOD) treatment with inconclusive or even conflicting results. However, most previous studies have neither been sufficiently stratified nor used matching or weighting methods to address severe confounding. In the present study, we aimed to determine the disparities between sexes after percutaneous endovascular revascularization (ER) for symptomatic PAOD. METHODS: Health insurance claims data from the second-largest insurance fund in Germany, BARMER, were used. A large cohort of patients who had undergone index percutaneous ER of symptomatic PAOD from January 1, 2010 to December 31, 2018 were included in the present study. The study cohort was stratified by the presence of intermittent claudication, ischemic rest pain, and wound healing disorders. Propensity score matching was used to adjust for confounding through differences in age, treated vessel region, comorbidities, and pharmacologic treatment. Sex-related differences regarding cardiovascular event-free survival, amputation-free survival, and overall survival within 5 years of surgery were determined using Kaplan-Meier time-to-event curves, log-rank test, and Cox regression analysis. RESULTS: In the present study, 50,051 patients (47.2% women) were identified and used to compose a matched cohort of 35,232 patients. Among all strata, female patients exhibited lower mortality (hazard ratio [HR], 0.69-0.90), fewer amputations or death (HR, 0.70-0.89), and fewer cardiovascular events or death (HR, 0.78-0.91). The association between female sex and improved long-term outcomes was most pronounced for the patients with intermittent claudication. CONCLUSIONS: In the present propensity score-matched analysis of health insurance claims, we observed superior cardiovascular event-free survival, amputation-free survival, and overall survival during 5 years of follow-up after percutaneous ER in women with symptomatic PAOD. Future studies should address sex disparities in the open surgical treatment of PAOD to illuminate whether the conflicting data from previous reports might have resulted from insufficient stratification of the studies.