Temporal Trends in Incidence Rates of Lower Extremity Amputation and Associated Risk Factors Among Patients Using Veterans Health Administration Services From 2008 to 2018

Analysis of Oklahoma amputation trends and identification of risk factors to target areas for limb preservation interventions

OBJECTIVE

Annual trends of lower extremity amputation due to end-stage chronic disease are on the rise in the United States. These amputations are leading to massive expenses for patients and the medical system. In Oklahoma, we have a high-risk population because access to care is low, the number of uninsured is high, cardiovascular health is poor, and our overall health care performance is ranked 50th in the country. But we know little about Oklahomans and their risk of limb loss. It is, therefore, imperative to look closely at this population to discover contemporary rates, trends, and state-specific risk factors for amputation due to diabetes and/or peripheral arterial disease (PAD). We hypothesize that state-specific groups will be identified as having the highest risk for limb loss and that contemporary trends in amputations are rising. To create implementable solutions to limb preservation, a baseline must be set.

METHODS

We conducted a 12-consecutive-year observational study using Oklahoma's hospital discharge data. Discharges among patients 20 years or older with a primary or secondary diagnosis of diabetes and/or PAD were included. Diagnoses and amputation procedures were identified using International Classification of Disease-9 and -10 codes. Amputation rates were calculated per 1000 discharges. Trends in amputation rates were measured by annual percentage changes (APC). Prevalence ratios evaluated the differences in amputation rates across demographic groups.

RESULTS

Over 5,000,000 discharges were identified from 2008 to 2019. Twenty-four percent had a diagnosis of diabetes and/or PAD. The overall amputation rate was 12 per 1000 discharges for those with diabetes and/or PAD. Diabetes and/or PAD-related amputation rates increased from 8.1 to 16.2 (APC, 6.0; 95% confidence interval [CI], 4.7-7.3). Most amputations were minor (59.5%), and although minor, increased at a faster rate compared with major amputations (minor amputation APC, 8.1; 95% CI, 6.7-9.6 vs major amputation APC, 3.1; 95% CI, 1.5-4.7); major amputations were notable in that they were significantly increasing. Amputation rates were the highest among males (16.7), American Indians (19.2), uninsured (21.2), non-married patients (12.7), and patients between 45 and 49 years of age (18.8), and calculated prevalence ratios for each were significant (P = .001) when compared within their respective category.

CONCLUSIONS

Amputation rates in Oklahoma have nearly doubled in 12 years, with both major and minor amputations significantly increasing. This study describes a worsening trend, underscoring that amputations due to chronic disease is an urgent statewide health care problem. We also present imperative examples of amputation health care disparities. By defining these state-specific areas and populations at risk, we have identified areas to pursue and improve care. These distinctive risk factors will help to frame a statewide limb preservation intervention.

Patterns of inpatient acute care and emergency department utilization within one year post-initial amputation among individuals with dysvascular major lower extremity amputation in Ontario, Canada: A population-based retrospective cohort study

INTRODUCTION

Lower extremity amputation (LEA) is a life altering procedure, with significant negative impacts to patients, care partners, and the overall health system. There are gaps in knowledge with respect to patterns of healthcare utilization following LEA due to dysvascular etiology.

OBJECTIVE

To examine inpatient acute and emergency department (ED) healthcare utilization among an incident cohort of individuals with major dysvascular LEA 1 year post-initial amputation; and to identify factors associated with acute care readmissions and ED visits.

DESIGN

Retrospective cohort study using population-level administrative data.

SETTING

Ontario, Canada.

POPULATION

Adults individuals (18 years or older) with a major dysvascular LEA between April 1, 2004 and March 31, 2018.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Acute care hospitalizations and ED visits within one year post-initial discharge.

RESULTS

A total of 10,905 individuals with major dysvascular LEA were identified (67.7% male). There were 14,363 acute hospitalizations and 19,660 ED visits within one year post-discharge from initial amputation acute stay. The highest common risk factors across all the models included age of 65 years or older (versus less than 65 years), high comorbidity (versus low), and low and moderate continuity of care (versus high). Sex differences were identified for risk factors for hospitalizations, with differences in the types of comorbidities increasing risk and geographical setting.

CONCLUSION

Persons with LEA were generally more at risk for acute hospitalizations and ED visits if higher comorbidity and lower continuity of care. Clinical care efforts might focus on improving transitions from the acute setting such as coordinated and integrated care for sub-populations with LEA who are more at risk.

The Effect of Prosthetic Limb Sophistication and Amputation Level on Self-reported Mobility and Satisfaction With Mobility

OBJECTIVE

To determine if lower limb prosthesis (LLP) sophistication is associated with patient-reported mobility and/or mobility satisfaction, and if these associations differ by amputation level.

DESIGN

Cohort study that identified participants through a large national database and prospectively collected self-reported patient outcomes.

SETTING

The Veterans Administration (VA) Corporate Data Warehouse, the National Prosthetics Patient Database, participant mailings, and phone calls.

PARTICIPANTS

347 Veterans who underwent an incident transtibial (TT) or transfemoral (TF) amputation due to diabetes and/or peripheral artery disease and received a qualifying LLP between March 1, 2018, and November 30, 2020.

INTERVENTIONS

Basic, intermediate, and advanced prosthesis sophistication was measured by the accurate and reliable PROClass system.

MAIN OUTCOME MEASURE

Patient-reported mobility using the advanced mobility subscale of the Locomotor Capabilities Index-5; mobility satisfaction using a 0-10-point Likert scale.

RESULTS

Lower limb amputees who received intermediate or advanced prostheses were more likely to achieve advanced mobility than those who received basic prostheses, with intermediate nearing statistical significance at nearly twice the odds (adjusted odds ratio (aOR)=1.8, 95% confidence interval (CI), .98-3.3; P=.06). The association was strongest in TF amputees with over 10 times the odds (aOR=10.2, 95% CI, 1.1-96.8; P=.04). The use of an intermediate sophistication prosthesis relative to a basic prosthesis was significantly associated with mobility satisfaction (adjusted β coefficient (aβ)=.77, 95% CI, .11-1.4; P=.02). A statistically significant association was only observed in those who underwent a TT amputation (aβ=.79, 95% CI, .09-1.5; P=.03).

CONCLUSIONS

Prosthesis sophistication was not associated with achieving advanced mobility in TT amputees but was associated with greater mobility satisfaction. In contrast, prosthesis sophistication was associated with achieving advanced mobility in TF amputees but was not associated with an increase in mobility satisfaction.

Regional Anesthesia is Associated with Improved Mortality and Morbidity in Patients with Congestive Heart Failure Undergoing Lower Extremity Amputation

BACKGROUND

While existing literature reports variable results of general anesthesia (GA) and regional anesthesia (RA) in patients undergoing lower extremity amputation (LEA), the effect of RA on patients with congestive heart failure (CHF) has not been explored. This study aims to assess whether the choice of anesthesia plays a role in influencing outcomes within this vulnerable population.

METHODS

Using the American College of Surgeons National Surgical Quality Improvement Program files between 2005 and 2022, all patients receiving LEA were identified, and the subset of patients with CHF was included. Patient characteristics and 30-day outcomes were compared using χ2 or Fischer's exact test as appropriate for categorical variables and the independent t-test or Mann-Whitney U test as appropriate for continuous variables. The association between anesthesia modality and post-operative outcomes was studied using multivariable logistic regression analysis.

RESULTS

A total of 5,831 patients (4,779 undergoing GA, 1,052 undergoing RA) with a diagnosis of CHF undergoing LEA were identified. On multivariable logistic regression analysis, RA was associated with lower mortality (adjusted odds ratio [aOR] 0.79, 95% CI 0.65-0.97), pneumonia (aOR 0.76, 95% CI 0.58-0.99), septic shock (aOR 0.64, 95% CI 0.47-0.88), post-operative blood transfusion (aOR 0.82, 95% CI 0.70-0.97), and 30-day readmission (aOR 0.79, 95% CI 0.64-0.97).

CONCLUSIONS

This study demonstrates that RA for LEA in patients with CHF is associated with decreased morbidity and mortality compared to GA. While furthermore research is needed to confirm this association, RA should be at least considered in CHF patients undergoing LEA when feasible.

Three-year outcomes of post-acute sequelae of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes post-acute sequelae of coronavirus disease 2019 (COVID-19) (PASC) in many organ systems. Risks of these sequelae have been characterized up to 2 years after infection, but longer-term follow-up is limited. Here we built a cohort of 135,161 people with SARS-CoV-2 infection and 5,206,835 controls from the US Department of Veterans Affairs who were followed for 3 years to estimate risks of death and PASC. Among non-hospitalized individuals, the increased risk of death was no longer present after the first year of infection, and risk of incident PASC declined over the 3 years but still contributed 9.6 (95% confidence interval (CI): 0.4-18.7) disability-adjusted life years (DALYs) per 1,000 persons in the third year. Among hospitalized individuals, risk of death declined but remained significantly elevated in the third year after infection (incidence rate ratio: 1.29 (95% CI: 1.19-1.40)). Risk of incident PASC declined over the 3 years, but substantial residual risk remained in the third year, leading to 90.0 (95% CI: 55.2-124.8) DALYs per 1,000 persons. Altogether, our findings show reduction of risks over time, but the burden of mortality and health loss remains in the third year among hospitalized individuals.

Sarcopenia and mild kidney dysfunction and risk of all-cause and cause-specific mortality in older adults

BACKGROUND

Sarcopenia has been identified as a risk factor for increased mortality in individuals with CKD. However, when considering individuals with mild kidney dysfunction prior to CKD, the impact of sarcopenia on adverse outcomes, particularly mortality, remains uncertain.

METHODS

This study included 323 801 participants from the UK Biobank. Mild kidney dysfunction was defined as estimated glomerular filtration rate between 60 and 89.9 mL/min/1.73 m2, and sarcopenia was defined according to the criteria of the 2019 European Working Group of Sarcopenia in Older People. Cox proportional hazard models with inverse probability weighting and competing risk models were used for analysis.

RESULTS

During a median follow-up of 11.8 years, 20 146 participants died from all causes. Compared with participants with normal kidney function and without sarcopenia, those with mild kidney dysfunction or sarcopenia had significantly increased risks of all-cause mortality [hazard ratio (HR) 1.16, 95% confidence interval (CI) 1.12-1.19; HR 1.29, 95% CI 1.20-1.37]; those with both mild kidney dysfunction and sarcopenia had an even higher risk of all-cause mortality (HR 1.61, 95% CI 1.52-1.71), with a significant overall additive interaction (relative risk due to interaction 0.17, 95% CI 0.05-0.29). Further subgroup analyses revealed that the associations of probable sarcopenia with all-cause and cause-specific mortality (non-accidental cause, non-communicable diseases and cancer) were stronger among participants with mild kidney dysfunction than those with normal kidney function.

CONCLUSIONS

The study indicates that sarcopenia and mild kidney dysfunction synergistically increase the risk of all-cause and cause-specific mortality. Early recognition and improvement of mild kidney function or sarcopenia in older people may reduce mortality risk but would require more prospective confirmation.

Ambient fine particulate matter chemical composition associated with in-hospital case fatality, hospital expenses, and length of hospital stay among patients with heart failure in China

*Joint senior authorship.

BACKGROUND

Previous studies have observed the adverse effects of ambient fine particulate matter pollution (PM2.5) on heart failure (HF). However, evidence regarding the impacts of specific PM2.5 components remains scarce.

METHODS

We included 58 129 patients hospitalised for HF between 2013 and 2017 in 11 cities of Shanxi, China from inpatient discharge database. We evaluated exposure to PM2.5 and its components ((sulphate (SO42-), nitrate (NO3-), ammonium (NH4+), organic matter (OM) and black carbon (BC)), along with meteorological factors using bilinear interpolation at each patients' residential address. We used multivariable logistic and linear regression models to assess the associations of these components with in-hospital case fatality, hospital expenses, and length of hospital stay.

RESULTS

Increase equivalents to the interquartile range (IQR) in OM (odds ratio (OR) = 1.13; 95% confidence interval (CI) = 1.02, 1.26) and BC (OR = 1.14; 95% CI = 1.02, 1.26) were linked to in-hospital case fatality. Per IQR increments in PM2.5, SO42-, NO3-, OM, and BC were associated with cost increases of 420.62 (95% CI = 285.75, 555.49), 221.83 (95% CI = 96.95, 346.71), 214.93 (95% CI = 68.66, 361.21), 300.06 (95% CI = 176.96, 423.16), and 303.09 (95% CI = 180.76, 425.42) CNY. Increases of 1 IQR in PM2.5, SO42-, OM, and BC were associated with increases in length of hospital stay of 0.10 (95% CI = 0.02, 0.19), 0.09 (95% CI = 0.02, 0.17), 0.10 (95% CI = 0.03, 0.17), and 0.16 (95% CI = 0.08, 0.23) days.

CONCLUSIONS

Our findings suggest that ambient SO42-, OM, and BC might be significant risk factors for HF, emphasising the importance of formulating customised guidelines for the chemical constituents of PM and controlling the emissions of the most dangerous components.

Effect of chronic kidney disease induced calcification on peripheral vascular perfusion using near-infrared spectroscopic imaging

Low-cost techniques that can detect the presence of vascular calcification (VC) in chronic kidney disease (CKD) patients could improve clinical outcomes. In this study, we established a near-infrared spectroscopy-based imaging technique to determine changes in peripheral hemodynamics due to CKD-induced VC. Mice were fed a high-adenine diet with either normal or high levels of phosphate to induce CKD with and without VC, respectively. The mice tail was imaged to evaluate hemodynamic changes in response to occlusion. The rate of change in oxyhemoglobin in response to occlusion showed a statistically significant difference in the presence of VC in the mice.

Amputation Rates and Associated Social Determinants of Health in the Most Populous US Counties

Importance

Social Determinants of Health (SDOH) have been found to be associated with health outcome disparities in patients with peripheral artery disease (PAD). However, the association of specific components of SDOH and amputation has not been well described.

Objective

To evaluate whether individual components of SDOH and race are associated with amputation rates in the most populous counties of the US.

Design, Setting, and Participants

In this population-based cross-sectional study of the 100 most populous US counties, hospital discharge rates for lower extremity amputation in 2017 were assessed using the Healthcare Cost and Utilization Project State Inpatient Database. Those data were matched with publicly available demographic, hospital, and SDOH data. Data were analyzed July 3, 2022, to March 5, 2023.

Main outcome and Measures

Amputation rates were assessed across all counties. Counties were divided into quartiles based on amputation rates, and baseline characteristics were described. Unadjusted linear regression and multivariable regression analyses were performed to assess associations between county-level amputation and SDOH and demographic factors.

Results

Amputation discharge data were available for 76 of the 100 most populous counties in the United States. Within these counties, 15.3% were African American, 8.6% were Asian, 24.0% were Hispanic, and 49.6% were non-Hispanic White; 13.4% of patients were 65 years or older. Amputation rates varied widely, from 5.5 per 100 000 in quartile 1 to 14.5 per 100 000 in quartile 4. Residents of quartile 4 (vs 1) counties were more likely to be African American (27.0% vs 7.9%, P < .001), have diabetes (10.6% vs 7.9%, P < .001), smoke (16.5% vs 12.5%, P < .001), be unemployed (5.8% vs 4.6%, P = .01), be in poverty (15.8% vs 10.0%, P < .001), be in a single-parent household (41.9% vs 28.6%, P < .001), experience food insecurity (16.6% vs 12.9%, P = .04), or be physically inactive (23.1% vs 17.1%, P < .001). In unadjusted linear regression, higher amputation rates were associated with the prevalence of several health problems, including mental distress (β, 5.25 [95% CI, 3.66-6.85]; P < .001), diabetes (β, 1.73 [95% CI, 1.33-2.15], P < .001), and physical distress (β, 1.23 [95% CI, 0.86-1.61]; P < .001) and SDOHs, including unemployment (β, 1.16 [95% CI, 0.59-1.73]; P = .03), physical inactivity (β, 0.74 [95% CI, 0.57-0.90]; P < .001), smoking, (β, 0.69 [95% CI, 0.46-0.92]; P = .002), higher homicide rate (β, 0.61 [95% CI, 0.45-0.77]; P < .001), food insecurity (β, 0.51 [95% CI, 0.30-0.72]; P = .04), and poverty (β, 0.46 [95% CI, 0.32-0.60]; P < .001). Multivariable regression analysis found that county-level rates of physical distress (β, 0.84 [95% CI, 0.16-1.53]; P = .03), Black and White racial segregation (β, 0.12 [95% CI, 0.06-0.17]; P < .001), and population percentage of African American race (β, 0.06 [95% CI, 0.00-0.12]; P = .03) were associated with amputation rate.

Conclusions and Relevance

Social determinants of health provide a framework by which the associations of environmental factors with amputation rates can be quantified and potentially used to guide interventions at the local level.

Examining health care access disparities in Hispanic populations with peripheral artery disease and diabetes

INTRODUCTION

This study investigated disparities in health care access for Hispanic adults with diabetes and peripheral artery disease (PAD) who are at risk of lower-extremity amputation and other cardiovascular morbidities and mortalities.

METHODS

We utilized the health care access survey data from the All of Us research program to examine adults (⩾ 18 years) with either diabetes and/or PAD. The primary associations evaluated were: could not afford medical care and delayed getting medical care in the past 12 months. Multivariable logistic regression models were used to assess the association of Hispanic ethnicity and survey responses, adjusting for age, sex, income, health insurance, and employment status.

RESULTS

Among 24,104 participants, the mean age was 54.9 years and 67% were women. Of these, 8.2% were Hispanic adults. In multivariable analysis, Hispanic adults were more likely to be unable to afford seeing a health care provider, and receiving emergency care, follow-up care, and prescription medications (p < 0.05) than non-Hispanic adults. Furthermore, Hispanic adults were more likely to report being unable to afford medical care due to cost (odds ratios [OR] 1.72, 95% CI 1.50-1.99), more likely to purchase prescription drugs from another country (OR 2.20, 95% CI 1.69-2.86), and more likely to delay getting medical care due to work (OR 1.46, 95% CI 1.22-1.74) and child care (OR 1.80, 95% CI 1.35-2.39) issues than non-Hispanic White adults.

CONCLUSION

The Hispanic population with diabetes and PAD faces substantial barriers in health care access, including a higher likelihood of delaying medical care and being unable to afford it.

The effects of long-term exposure to air pollution on incident mental disorders among patients with prediabetes and diabetes: Findings from a large prospective cohort

BACKGROUND

The association between air pollution and mental disorders has been widely documented in the general population. However, the evidence among susceptible populations, such as individuals with prediabetes or diabetes, is still insufficient.

METHODS

We analyzed data from 48,515 participants with prediabetes and 24,393 participants with diabetes from the UK Biobank. Annual pollution data were collected for fine particulate matter (PM2.5), inhalable particulate matter (PM10), nitrogen dioxide (NO2), and nitrogen dioxides (NOx) during 2006-2021. The exposure to air pollution and temperature for each participant were estimated by the bilinear interpolation approach and time-weighted method based on their geocoded home addresses and time spent at each address. We employed the generalized propensity score model based on the generalized estimating equation and the time-varying covariates Cox model to assess the effects of air pollution.

RESULTS

We observed causal links between air pollutants and mental disorders among both prediabetic and diabetic participants, with stronger effects among those with diabetes than prediabetes. The hazard ratios were 1.18 (1.12, 1.24), 1.15 (1.10, 1.20), 1.18 (1.13, 1.23), and 1.15 (1.11, 1.19) in patients with prediabetes, and 1.21 (1.13, 1.29), 1.17 (1.11, 1.24), 1.19 (1.13, 1.25), and 1.17 (1.12, 1.23) in patients with diabetes per interquartile range elevation in PM2.5, PM10, NO2, and NOx. Furthermore, the effects were more pronounced among people who were older, alcohol drinkers, and living in urban areas.

CONCLUSIONS

Our study indicates the potential causal links between long-term exposure to air pollution and incident mental disorders among those with prediabetes and diabetes. Reducing air pollution levels would significantly benefit this vulnerable population by reducing the incidence of mental disorders.

Plantar somatosensory restoration enhances gait, speed perception, and motor adaptation

Lower limb loss is a major insult to the body's nervous and musculoskeletal systems. Despite technological advances in prosthesis design, artificial limbs are not yet integrated into the body's physiological systems. Therefore, lower limb amputees (LLAs) experience lower balance confidence, higher fear of falls, and impaired gait compared with their able-bodied peers (ABs). Previous studies have demonstrated that restored sensations perceived as originating directly from the missing limb via neural interfaces improve balance and performance in certain ambulatory tasks; however, the effects of such evoked sensations on neural circuitries involved in the locomotor activity are not well understood. In this work, we investigated the effects of plantar sensation elicited by peripheral nerve stimulation delivered by multicontact nerve cuff electrodes on gait symmetry and stability, speed perception, and motor adaptation. We found that restored plantar sensation increased stance time and propulsive force on the prosthetic side, improved gait symmetry, and yielded an enhanced perception of prosthetic limb movement. Our results show that the locomotor adaptation among LLAs with plantar sensation became similar to that of ABs. These findings suggest that our peripheral nerve-based approach to elicit plantar sensation directly affects central nervous pathways involved in locomotion and motor adaptation during walking. Our neuroprosthesis provided a unique model to investigate the role of somatosensation in the lower limb during walking and its effects on perceptual recalibration after a locomotor adaptation task. Furthermore, we demonstrated how plantar sensation in LLAs could effectively increase mobility, improve walking dynamics, and possibly reduce fall risks.

The relationship between lower extremity amputation and body mass index

OBJECTIVES

Non-traumatic lower extremity amputation (LEA) is associated with significant morbidity and mortality. Diabetes mellitus (DM) and peripheral vascular disease (PVD) are associated with increased risk for LEA. As such, DM and PVD account for 54% of all LEA's, performed in the United States annually. As obesity is highly associated with both DM and PVD, our study sought to explore the relationship between LEA and obesity defined by BMI.

METHODS

Using the National Inpatient Sample (NIS) database, a retrospective review of patients who underwent non-traumatic LEA (LEA) between 2008 and 2014 was performed. The International Classification of Diseases 9th edition (ICD-9) codes were utilized to determine the diagnoses, comorbidities, and procedures. Patient BMIs were classified as follows: Non-obese [BMI <30], Obesity class I [BMI 30-34.9], Obesity class II [BMI 35-39.9], and Obesity class III [BMI ≥40]. Predictors for LEA were compared between groups using chi-square test and binary logistic regression to identify possible underlying factors associated with LEA. We also conducted a multivariate analysis to measure the effect of multiple variables on LEA.

RESULTS

We identified 16,259 patients with non-traumatic LEA and a mean age of 59.9 years. Rate of amputation in females was lower than males at 0.35% vs 0.87% respectively (p < 0.001). Of patients that underwent amputation there was a V-shape trend based on BMI, with 30.4% in non-obese patients, 18.2% in obesity class I, 17.3% in obesity class II, and 34.1% in obesity class III. The incidence of diabetes increased with obesity class, while the incidence of PVD decreased. Interestingly, of those with DM there was an inverse relationship between amputation rate and BMI class, with LEA rates in non-obese versus obesity class III patients were 1.63% vs 0.98% respectively (p < 0.001). Similarly, patients who had both diabetes and PVD showed a downward trend in LEA rate as obesity class increased; non-obese patients had a LEA rate of 8.01%, while obesity class III had 4.65% (p < 0.001). Patients in higher income bracket have lower odds of LEA (OR 0.77, p < 0.001) compared to the lowest income patients. Also, patients with comorbidities such as PVD (OR 10.78), diabetes (OR 5.02), renal failure (OR 1.41), and hypertension (OR 1.36) had higher odds to get an LEA (p < 0.001). Individuals with obesity class III are almost at half the odds (OR 0.52) to get an LEA compared to non-obese (p < 0.001).

CONCLUSIONS

Higher BMI and female gender are protective factors against lower extremity amputation. Factors that predisposing to LEA include lower household income and certain comorbidities such as PVD, diabetes, renal failure, and hypertension. These findings warrant further research to identify patients at high risk for LEA and help develop management guidelines for targeted populations.

Comparative effectiveness of SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors, and sulfonylureas on risk of major adverse cardiovascular events: emulation of a randomised target trial using electronic health records

BACKGROUND

Randomised clinical trials showed that compared with placebo, SGLT2 inhibitors and GLP-1 receptor agonists reduced risk of adverse cardiovascular events. The evidence base for the older antihyperglycaemic drug classes (DPP-4 inhibitors and sulfonylureas) is generally less well developed. Because most randomised trials evaluated one antihyperglycaemic medication versus placebo, a head-to-head comparative effectiveness analysis of the newer drug classes (SGLT2 inhibitors vs GLP-1 receptor agonists) or newer (SGLT2 inhibitors or GLP-1 receptor agonists) versus older (DPP-4 inhibitors or sulfonylureas) drug classes on risk of major adverse cardiovascular events (MACE) is not available. In this study, we aimed to evaluate the comparative effectiveness of incident use of SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors, or sulfonylureas on risk of MACE.

METHODS

We first specified the protocol of a four-arm randomised pragmatic clinical trial and then emulated it using the health-care databases of the US Department of Veterans Affairs. We built a cohort of metformin users with incident use of SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors, or sulfonylureas between Oct 1, 2016 and Sept 30, 2021, and followed up until Dec 31, 2022. We used the overlap weighting approach to balance the treatment groups using a battery of predefined variables and a set of algorithmically selected variables from high-dimensional data domains. Both intention-to-treat and per-protocol analyses (the latter estimated the effect of maintained use of the antihyperglycaemic throughout follow-up) were conducted to estimate risk of MACE-defined as a composite endpoint of stroke, myocardial infarction, and all-cause mortality.

FINDINGS

The final cohort consisted of 283 998 new users of SGLT2 inhibitors (n=46 516), GLP-1 receptor agonists (n=26 038), DPP-4 inhibitors (n=55 310), or sulfonylureas (n=156 134). In intention-to-treat analyses, compared with sulfonylureas, SGLT2 inhibitors, GLP-1 receptor agonists, and DPP-4 inhibitors were associated with lower risk of MACE (hazard ratio [HR] 0·77 [95% CI 0·74-0.80], 0·78 [0·74-0·81), and 0·90 [0·86-0.93], respectively). Both SGLT2 inhibitors and GLP-1 receptor agonists were associated with a lower risk of MACE when compared with DPP-4 inhibitors (HR 0·86 [0·82-0·89] and 0·86 [0·82-0·90], respectively). The risk of MACE between SGLT2 inhibitors and GLP-1 receptor agonists yielded an HR of 0·99 (0·94-1·04). In per-protocol analyses, compared with sulfonylureas, SGLT2 inhibitors, GLP1 receptor agonists, and DPP-4 inhibitors were associated with reduced risk of MACE (HR 0·77 [95% CI 0·73-0·82], 0·77 [0·72-0·82], and 0·88 [0·83-0·93], respectively). Both SGLT2 inhibitors and GLP-1 receptor agonists were associated with a lower risk of MACE when compared with DPP-4 inhibitors (HR 0·88 [0·83-0·93] and 0·88 [0·82-0·93], respectively). The risk of MACE between SGLT2 inhibitors and GLP-1 receptor agonists yielded an HR of 1·01 (0·94-1·07).

INTERPRETATION

Both SGLT2 inhibitors and GLP-1 receptor agonists were associated with reduced risk of MACE compared with DPP-4 inhibitors or sulfonylureas. DPP-4 inhibitors were associated with reduced risk of MACE compared with sulfonylureas. There was no statistically significant difference in risk of MACE between SGLT2 inhibitors and GLP-1 receptor agonists. The results provide evidence of the real-world comparative effectiveness of the four most commonly used second-line antihyperglycaemics and could guide choice of antihyperglycaemic therapy.

FUNDING

US Department of Veterans Affairs and the American Society of Nephrology.

Association of Health Care Utilization and Access to Care With Vascular Assessment Before Major Lower Extremity Amputation Among US Veterans

Importance

Patient-level characteristics alone do not account for variation in care among US veterans with peripheral artery disease (PAD). Presently, the extent to which health care utilization and regional practice variation are associated with veterans receiving vascular assessment prior to major lower extremity amputation (LEA) is unknown.

Objective

To assess whether demographics, comorbidities, distance to primary care, the number of ambulatory clinic visits (primary and medical specialty care), and geographic region are associated with receipt of vascular assessment prior to LEA.

Design, Setting, and Participants

This national cohort study used US Department of Veterans Affairs' Corporate Data Warehouse data from March 1, 2010, to February 28, 2020, for veterans aged 18 or older who underwent major LEA and who received care at Veterans Affairs facilities.

Exposures

The number of ambulatory clinic visits (primary and medical specialty care) in the year prior to LEA, geographic region of residence, and distance to primary care.

Main Outcomes and Measures

The main outcome was receipt of a vascular assessment (vascular imaging study or revascularization procedure) in the year prior to LEA.

Results

Among 19 396 veterans, the mean (SD) age was 66.78 (10.20) years and 98.5% were male. In the year prior to LEA, 8.0% had no primary care visits and 30.1% did not have a vascular assessment. Compared with veterans with 4 to 11 primary care clinic visits, those with fewer visits were less likely to receive vascular assessment in the year prior to LEA (1-3 visits: adjusted odds ratio [aOR], 0.90; 95% CI, 0.82-0.99). Compared with veterans who lived less than 13 miles from the closest primary care facility, those who lived 13 miles or more from the facility were less likely to receive vascular assessment (aOR, 0.88; 95% CI, 0.80-0.95). Veterans who resided in the Midwest were most likely to undergo vascular assessment in the year prior to LEA than were those living in other regions.

Conclusions and Relevance

In this cohort study, health care utilization, distance to primary care, and geographic region were associated with intensity of PAD treatment before LEA, suggesting that some veterans may be at greater risk of suboptimal PAD care practices. Development of clinical programs, such as remote patient monitoring and management, may represent potential opportunities to improve limb preservation rates and the overall quality of vascular care for veterans.

Lower-limb peripheral arterial disease and amputations in people with diabetes: Risk factors, prognostic value and management

Lower-limb peripheral arterial disease (PAD), is a common manifestation of systemic atherosclerosis, resulting from a partial or complete obstruction of at least one lower-limb arteries. PAD is a major endemic disease with an excess risk of major cardiovascular events and death. It also leads to disability, high rates of lower-limb adverse events and non-traumatic amputation. In patients with diabetes, PAD is particularly frequent and has a worse prognosis than in patients without diabetes. The risk factors of PAD are comparable to those for cardiovascular disease. The ankle-brachial index is usually recommended to screen PAD despite its limited performance in patients with diabetes, affected by the presence of peripheral neuropathy, medial arterial calcification, incompressible arteries and infection. Toe brachial index and toe pressure emerge as alternative screening tools. The management of PAD requires strict control of cardiovascular risk factors including diabetes, hypertension and dyslipidaemia, the use of antiplatelet agents and lifestyle management, to reduce cardiovascular adverse events, but few randomized controlled trials have evaluated the benefits of these treatments in PAD. Several advances have been achieved in endovascular and surgical revascularization procedures, with obvious improvement in PAD prognosis. Further studies are required to increase our understanding of the pathophysiology of PAD and to evaluate the interest of different therapeutic strategies in the occurrence and progression of PAD in patients with diabetes. Here, we present a narrative and contemporary review to synthesize the key epidemiology findings, screening and diagnosis methods, and major therapeutic advances regarding PAD in patients with diabetes.

Annual Foot Exams are Associated with Reduced Incident Amputation among Older Veterans with Diabetes

We conducted a secondary data analysis to evaluate the association between annual foot exams and incident lower extremity amputations (LEA) among older veterans with diabetes during FY2007-FY2014. Older Veterans with at least one primary care provider visit each year (N = 664,162) and at least one foot exam each year (N = 72,892) and the overlap were identified from the 5 years prior to the study period of interest (FY2002-FY2006 (N = 71,122)). After excluding incident LEA related to cancer and trauma, 71,018 veterans (mean age +/- SD, % male) were included in the final cohort, which was followed from FY2007-FY2014 to evaluate the influence of subsequent annual foot exams and incident LEA. Consistent annual foot exams were protective for incident LEA in older veterans with diabetes, adjusted OR was 0.85 (97% CI: 0.74-0.96). Results indicate that adherence to annual foot exam guidelines can reduce incident LEA in older veterans with diabetes.

Ambient particulate matter pollution of different sizes associated with recurrent stroke hospitalization in China: A cohort study of 1.07 million stroke patients

BACKGROUND

To estimate the associations between ambient particulate matter (PM) pollution of different sizes (PM₁, PM_2.5, and PM₁₀) and risk of rehospitalization among stroke patients, as well as the attributable burden in China.

METHODS

We built a cohort of 1,066,752 participants with an index stroke hospitalization in Sichuan, China from 2017 to 2019. Seven-day and annual average exposures to PM pollution prior to the date of the index hospitalization were linked with residential address using a bilinear interpolation approach. Cox proportional hazard models were constructed to assess the association between ambient PM and the risk of rehospitalization. The burden of stroke rehospitalization was estimated using a counterfactual approach.

RESULTS

245,457 (23.0 %) participants experienced rehospitalization during a mean of 1.15 years (SD: 0.90 years) of follow-up. Seven-day average concentrations of PM were associated with increased risk of rehospitalization: the hazard ratios (HRs) per 10 μg/m³ were 1.034 (95 % confidence interval [CI]: 1.029-1.038) for PM₁, 1.033 (1.031-1.036) for PM_2.5, and 1.030 (1.028-1.031) for PM₁₀; the hazard ratios were larger for annual average concentrations: 1.082 (1.074-1.090) for PM₁, 1.109 (1.104-1.114) for PM_2.5, and 1.103 (1.099-1.106) for PM₁₀. The associations were stronger in participants who were female, of minority ethnicity (non-Han Chinese), who suffered from an ischemic stroke, and those admitted under normal conditions. Population attributable fractions for stroke rehospitalization ranged from 4.66 % (95 % CI: 1.69 % to 7.63 %) for the 7-day average of PM₁ to 17.05 % (14.27 % to 19.83 %) for the annual average of PM₁₀; the reducible average cost of rehospitalization per participant attributable to PM ranged from 492.09 (178.19 to 806) RMB for the 7-day average of PM₁ to 1801.65 (1507.89 to 2095.41) RMB for the annual average of PM₁₀.

CONCLUSIONS

Ambient PM pollution may increase the risk of rehospitalization in stroke patients and is responsible for a significant burden of stroke rehospitalization.

Amputation Acceptance: A Survey of Factors Influencing the Decision to Undergo Lower Extremity Amputation

Accepting to undergo amputation is an arduous process often fraught with confusion, fear, and uncertainty. To assess how to best facilitate discussions with at-risk patients, we surveyed lower extremity amputees about their experiences surrounding this decision-making process. Patients who underwent lower extremity amputation at our institution from October 2020 to October 2021 were asked to complete a 5-item telephone survey assessing their decision to undergo amputation and postoperative satisfaction. Retrospective chart review of respondent demographics, comorbidities, operative details, and complications was conducted. Of 89 lower extremity amputees identified, 41 (46.07%) responded to the survey, with the majority undergoing below-knee amputations (n = 34, 82.93%). At a mean follow-up of 5.90 ± 3.45 months, 20 patients (48.78%) were ambulatory. Surveys were completed at a mean of 7.74 ± 4.03 months since amputation. Factors that helped patients decide to undergo amputation included discussions with doctors (n = 32, 78.05%) and concern for worsening health (n = 19, 46.34%). Deteriorating ability to walk (n = 18, 45.00%) was the most common concern prior to surgery. Recommendations by survey respondents to ease the decision-making process included speaking with amputees (n = 9. 22.50%), more discussions with doctors (n = 8, 20.00%), and access to mental health and social services (n = 2, 5.00%); however, many had no recommendations (n = 19, 47.50%), and most were pleased with their decision to undergo amputation (n = 38, 92.68%). Despite most patients primarily citing satisfaction with their decision to undergo lower extremity amputation, it is critical to consider factors that affect patient decisions and recommendations to improve this decision-making process.

Exposure to Air Pollution during Pre-Hypertension and Subsequent Hypertension, Cardiovascular Disease, and Death: A Trajectory Analysis of the UK Biobank Cohort

BACKGROUND

The associations between air pollution exposure and morbidity and mortality of cardiovascular diseases (CVDs) have been widely reported; however, evidence on such associations across different dynamic disease trajectories remain unknown.

OBJECTIVE

We examined whether ambient air pollution during the prehypertension (pre-HTN) stage could aggravate the progression from hypertension (HTN) to CVD, and consequent death.

METHODS

A total of 168,010 adults with pre-HTN (120 - 139  mmHg systolic blood pressure or 80 - 89  mmHg diastolic blood pressure) from the UK Biobank were included in this analysis. We used a multistate model to explore the associations between five air pollutants (PM 2.5 , PM 2.5 absorbance, PM 10 , NO 2 , and NO x ) and the risk of six disease transitions (from pre-HTN to HTN, from pre-HTN to CVD, from pre-HTN to death, from HTN to CVD, from HTN to death, and from CVD to death). Mediation analyses were further conducted to explore the role of intermediate diseases in the dynamic progression of CVDs.

RESULTS

During a median follow-up of 12 y, 13,743 (8.18%) of participants with pre-HTN developed HTN, whereas 12,825 (7.63%) and 4,467 (2.66%) directly developed CVD or died, respectively. Air pollution was positively associated with the dynamic disease progression. For example, a per-interquartile range increase of PM 2.5 was significantly associated with the hazard ratios (HRs) of 1.105 [95% confidence intervals (CI): 1.083, 1.127], 1.045 (95% CI: 1.022, 1.068), and 1.086 (95% CI: 1.047, 1.126) in the transition from pre-HTN to HTN, CVD, and death, respectively. Higher levels of air pollution were associated with increased transition probability of disease progression. Mediation analyses indicated that intermediate diseases subsequently significantly mediated air pollutant-associated risk to develop more serious disease.

CONCLUSIONS

This study provides evidence that air pollution might play a role in the early stages of CVD progression. Controlling air pollution might be an effective measure to prevent CVD progression and reduce the disease burden of CVD. https://doi.org/10.1289/EHP10967.

Reduced Hospitalizations and Amputations in Patients with Diabetic Foot Ulcers Treated with Cyclical Pressurized Topical Wound Oxygen Therapy: Real-World Outcomes

Background: This study sought to examine the real-world impact of multimodality cyclical-pressure topical wound oxygen therapy (TWO2) on hospitalizations and amputations in patients with diabetic foot ulcer (DFU) compared with patients without TWO2. Methods: We conducted a retrospective review of deidentified patient medical records at 2 U.S. Veterans Affairs hospitals between January 2012 and January 2020. DFU patients were assigned to TWO2 or NO TWO2 cohorts based on their treatment records. Patients received appropriate standard of care and may have received other advanced wound treatments, including skin substitutes, negative pressure wound therapy, and growth factors. Primary study outcomes were patients requiring hospitalization and/or amputation within 360 days of initial wound documentation. Findings: Among unmatched cohorts of 202 patients with DFU (91 TWO2, 111 NO TWO2), 6.6% and 12.1% of TWO2 patients had hospitalizations and amputations, respectively, compared with 54.1% and 41.4% of NO TWO2 patients within 360 days (p < 0.0001, p < 0.0001), representing 88% and 71% reductions. Among propensity score-matched cohorts of 140 DFU patients (70 TWO2, 70 NO TWO2), compared with NO TWO2, 82% fewer TWO2 patients were hospitalized (7.1% vs. 40.0%, p < 0.0001) and 73% fewer TWO2 patients had amputations (8.6% vs. 31.4%, p = 0.0007). Logistic regression among matched cohorts demonstrated nearly ninefold and fivefold higher risk of hospitalization and amputation, respectively, for NO TWO2 versus TWO2. Interpretation: This retrospective cohort study demonstrates that treating patients with DFU with TWO2 is associated with significant reductions in hospitalizations and amputations in the real-world setting.

Transmetatarsal amputations in patients with diabetes mellitus: A contemporary analysis from an academic tertiary referral centre in a developing community

Transmetatarsal amputation (TMA) involves the surgical removal of the distal portion of metatarsals in the foot. It aims to maintain weight-bearing and independent ambulation while eliminating the risk of spreading soft tissue infection or gangrene. This study aimed to explore the risk factors and surgical outcomes of TMA in patients with diabetes at an academic tertiary referral center in Jordan. Medical records of all patients with diabetes mellitus who underwent TMA at King Abdullah University Hospital, Jordan, between January 2017 and January 2019 were retrieved. Patient characteristics along with clinical and laboratory findings were analyzed retrospectively. Pearson’s chi-square test of association, Student’s t-test, and multivariate regression analysis were used to identify and assess the relationships between patient findings and TMA outcome. The study cohort comprised 81 patients with diabetes who underwent TMA. Of these, 41 (50.6%) patients achieved complete healing. Most of the patients were insulin-dependent (85.2%). Approximately half of the patients (45.7%) had severe ankle-brachial index (ABI). Thirty patients (37.1%) had previous revascularization attempts. The presence of peripheral arterial disease (P<0.05) exclusively predicted poor outcomes among the associated comorbidities. Indications for TMA included infection, ischemia, or both. The presence of severe ABI (≤0.4, P<0.01) and a previous revascularization attempt (P<0.05) were associated with unfavorable outcomes of TMA. Multivariate analysis that included all demographic, clinical, and laboratory variables in the model revealed that insulin-dependent diabetes, low albumin level (< 33 g/L), high C-reactive protein level (> 150 mg/L), and low score of Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC, <6) were the main factors associated with poor TMA outcomes. TMA is an effective technique for the management of diabetic foot infection or ischemic necrosis. However, attention should be paid to certain important factors such as insulin dependence, serum albumin level, and LRINEC score, which may influence the patient’s outcome.

Temporal Trends, Practice Variation, and Associated Outcomes With IVUS Use During Peripheral Arterial Intervention

BACKGROUND

Intravascular ultrasound (IVUS) has been shown in limited prospective studies to improve procedural outcomes for patients undergoing lower extremity peripheral arterial intervention (PVI).

OBJECTIVES

The authors aimed to study temporal trends, practice variation, and associated outcomes with the use of IVUS during PVI among Medicare beneficiaries.

METHODS

All PVIs performed from 2016 to 2019 among Medicare beneficiaries aged >65 years were included. Temporal trends in IVUS use were stratified by procedural location (inpatient, outpatient, or ambulatory surgery center [ASC]/office-based laboratory [OBL]) and physician specialty. The primary outcome was major adverse limb events (MALE). Inverse probability weighting was used to account for differences in baseline characteristics. Cox regression with competing risks was used to estimate weighted hazard ratios.

RESULTS

During the study period, 543,488 PVIs were included, of which 63,372 (11.7%) used IVUS. A substantial growth in IVUS use was observed, which was driven by procedures performed in ASCs/OBLs (23.6% increase from quarter 1 of 2016 through quarter 4 of 2019). Among operators who used IVUS, there was also notable variation in use (median operator use 5.4% of cases; IQR: 2.2%-15.0%; range, <1%-100%). In weighted analysis, IVUS use during PVI was associated with a lower risk of MALE through a median of 514 days (adjusted hazard ratio: 0.73; 95% CI: 0.70-0.75; P < 0.0001).

CONCLUSIONS

In contemporary nationwide data, IVUS use during PVI has increased since 2016, driven by growth in the ASC/OBL setting. However, there remains substantial variation in operator practice. When used during PVI, IVUS was associated with a lower risk of short- and long-term MALE.

The impact of the demographic shift on limb amputation incidence in Saskatchewan, Canada, 2006–2019

Background

Changing demographics in a population may have an inevitable influence on disease incidence including limb amputation. However, the extent to which these changes affect limb amputation (LA) is unknown. Understanding the impact of changing demographics on LA would provide the best opportunity to plan for the future. We assessed the impact of changes in age and sex on limb amputation in Saskatchewan between 2006 and 2019.

Methods

Retrospective linked Saskatchewan’s LA cases, and demographic characteristics and residents population from 2006–2019 was used. The amputation rate was calculated by dividing the total number of LA cases recorded each year by the annual Saskatchewan resident population and the results expressed per 100,000 populations. Furthermore, decomposition analysis was used to assess the impact of changes in age and sex on LA in a decade (2008–2017) and the Generalized Additive Model (GAM) was employed to examine the linear and non-linear effect of age.

Results

We found that in the ten years (2008–2017), the absolute LA rate difference was 9.0 per 100,000 population. Changes in age structure alone contributed 7.7% to the LA rate increase and 92.3% to changes in age-specific LA rates. The decade witnessed a marginal population difference between males and females, but the LA rate was 2.1–2.2 times higher in males than in females. The GAM revealed a non-linear relationship between LA and age, and further indicates that the risk of LA significantly increased as age increases.

Conclusions

In a decade, we found that changes in age distribution and age-specific rate substantially impacted the increase in the LA rate observed in the province. This highlights the urgent need for strategized programs to respond to these changes as both the population and diabetes, which is age-dependent and a leading cause of LA, are expected to increase in the province by 2030. As changes in population and demographic factors are inevitable, this study provides data for policy makers on the need for continuous incorporation of the shift in population in the design of future health services.

Mortality and Conversion to Transfemoral Amputation After Transtibial Amputation in the Veterans Affairs Health System

INTRODUCTION

Transtibial below-knee amputation (BKA) is associated with considerable morbidity, particularly in the vasculopathic population. The purpose of this study was to determine the cumulative probability of undergoing transfemoral above-knee amputation (AKA) conversion within 5 years of BKA and associated risk factors while accounting for the competing risk of death.

METHODS

This is a retrospective, national database study with structured query of the Veterans Affairs (VA) database for patients who underwent BKA from 1999 to 2020, identified by Current Procedural Terminology codes. Above-knee amputation conversion was identified using Current Procedural Terminology codes in combination with natural language processing to match procedure laterality. After internally validating our patient identification method, risk factors were collected. Competing risk analysis estimated the cumulative incidence rate of AKA conversion and associated risk factors with death as a competing risk.

RESULTS

Our query yielded 19,875 patients (19,640 men, 98.8%) who underwent BKA with a median age of 66 years (interquartile range, 60 to 73). The median follow-up was 951 days (interquartile range, 275 to 2,026). The crude cumulative probabilities of AKA conversion and death at 5 years were 15.4% (95% confidence interval [CI], 14.9% to 16.0%) and 47.7% (95% CI, 46.9% to 48.4%), respectively. In the Fine and Gray subdistribution hazard model, peripheral vascular disease had the highest AKA conversion risk (hazard ratio [HR] 2.66; 95% CI, 2.22 to 3.20; P < 0.001). Other factors independently associated with AKA conversion included urgent operation (HR 1.32; 95% CI, 1.23 to 1.42), cerebrovascular disease (HR 1.19; 95% CI, 1.11 to 1.28), chronic obstructive pulmonary disease (HR 1.15; 95% CI, 1.07 to 1.24), and previous myocardial infarction (HR 1.10; 95% CI, 1.02 to 1.19) (All P < 0.02).

DISCUSSION

Within this predominantly male, VA population, BKA carries a high risk of conversion to AKA within 5 years, without reaching a steady risk of AKA conversion within 5 years. Peripheral vascular disease, chronic obstructive pulmonary disease, cerebrovascular disease, previous myocardial infarction, and urgent BKA increase the risk of AKA conversion.

LEVEL OF EVIDENCE

Level III.

The Chasm in Percutaneous Coronary Intervention and In-Hospital Mortality Rates Among Acute Myocardial Infarction Patients in Rural and Urban Hospitals in China: A Mediation Analysis

Objectives: To determine to what extent the inequality in the ability to provide percutaneous coronary intervention (PCI) translates into outcomes for AMI patients in China.

Methods: We identified 82,677 patients who had primary diagnoses of AMI and were hospitalized in Shanxi Province, China, between 2013 and 2017. We applied logistic regressions with inverse probability weighting based on propensity scores and mediation analyses to examine the association of hospital rurality with in-hospital mortality and the potential mediating effects of PCI.

Results: In multivariate models where PCI was not adjusted for, rural hospitals were associated with a significantly higher risk of in-hospital mortality (odds ratio [OR]: 1.19, 95% confidence interval [CI]: 1.03–1.37). However, this association was nullified (OR: 0.94, 95% CI: 0.81–1.08) when PCI was included as a covariate. Mediation analyses revealed that PCI significantly mediated 132.3% (95% CI: 104.1–256.6%) of the effect of hospital rurality on in-hospital mortality. The direct effect of hospital rurality on in-hospital mortality was insignificant.

Conclusion: The results highlight the need to improve rural hospitals’ infrastructure and address the inequalities of treatments and outcomes in rural and urban hospitals.

Design and Evaluation of a Knee Flexion Assistance Exoskeleton for People with Transtibial Amputation

People with below-knee amputation walk with asymmetric gaits that over time can lead to further musculoskeletal disorders and decreased quality of life. While prosthesis technology is improving, prosthetic ankles may be fundamentally limited in their ability to restore healthy walking patterns because they do not assist the residual knee joint. The knee on the residual limb has muscular deficits due to the loss of the gastrocnemius, a biarticular muscle that crosses both the ankle and knee. Here we present the design, development, and preliminary evaluation of a robotic knee exoskeleton for people with transtibial amputation. The device is intended to restore gastrocnemius-like flexion moments to the knee on the residual limb. The exoskeleton uses a custom offboard actuation and control system to allow for a simple and lightweight design with high torque capabilities. A preliminary walking experiment with one person with transtibial amputation was conducted. The exoskeleton provided a range of knee flexion torque profiles and had an RMS tracking error of 1.9 Nm across four assistance conditions. This device will be used in future studies to explore the effects of providing knee flexion assistance to people with transtibial amputation during walking. Long term, findings from studies with this exoskeleton could motivate future assistive device designs that improve walking mechanics and quality of life for people with limb loss.

Long COVID after breakthrough SARS-CoV-2 infection

The post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-also referred to as Long COVID-have been described, but whether breakthrough SARS-CoV-2 infection (BTI) in vaccinated people results in post-acute sequelae is not clear. In this study, we used the US Department of Veterans Affairs national healthcare databases to build a cohort of 33,940 individuals with BTI and several controls of people without evidence of SARS-CoV-2 infection, including contemporary (n = 4,983,491), historical (n = 5,785,273) and vaccinated (n = 2,566,369) controls. At 6 months after infection, we show that, beyond the first 30 days of illness, compared to contemporary controls, people with BTI exhibited a higher risk of death (hazard ratio (HR) = 1.75, 95% confidence interval (CI): 1.59, 1.93) and incident post-acute sequelae (HR = 1.50, 95% CI: 1.46, 1.54), including cardiovascular, coagulation and hematologic, gastrointestinal, kidney, mental health, metabolic, musculoskeletal and neurologic disorders. The results were consistent in comparisons versus the historical and vaccinated controls. Compared to people with SARS-CoV-2 infection who were not previously vaccinated (n = 113,474), people with BTI exhibited lower risks of death (HR = 0.66, 95% CI: 0.58, 0.74) and incident post-acute sequelae (HR = 0.85, 95% CI: 0.82, 0.89). Altogether, the findings suggest that vaccination before infection confers only partial protection in the post-acute phase of the disease; hence, reliance on it as a sole mitigation strategy may not optimally reduce long-term health consequences of SARS-CoV-2 infection. The findings emphasize the need for continued optimization of strategies for primary prevention of BTI and will guide development of post-acute care pathways for people with BTI.

Three Exposure Metrics for Fine Particulate Matter Associated With Outpatient Visits for Acute Lower Respiratory Infection Among Children in Guangzhou, China

Ambient fine particulate matter (PM_2.5) is associated with an elevated risk of acute lower respiratory infections (ALRI). However, this association has not been examined using alternative exposure metrics. We collected outpatient data of patients with ALRI aged <14 years from the administrative database of a large tertiary hospital in Guangzhou, China, from 2013 to 2019. Ambient PM_2.5 was measured using three metrics: (a) daily mean, (b) daily excessive concentration hours (DECH), and (c) hourly peak. Generalized additive models were fitted to estimate the excess risk (ER) associated with PM_2.5. A total of 105,639 ALRI (35,310 pneumonia and 68,218 bronchiolitis) outpatient visits were identified during the study period. An interquartile range increment in PM_2.5 DECH was consistently associated with the highest ER of ALRI-related outpatient visits: 12.30% (95% confidence interval [CI]: 9.49–15.18%), compared with 11.20% (95% CI: 8.34–14.13%) for daily mean and 9.73% (95% CI: 6.97–12.55%) for hourly peak. The associations between the three metrics of PM_2.5 and ALRI-related outpatient visits were stronger in the cold season than in the warm season. Future studies should consider PM_2.5 DECH as an alternative method of exposure measurement, in addition to daily mean and hourly peak concentrations of PM_2.5.

Association of Ambient Particulate Matter Pollution of Different Sizes With In-Hospital Case Fatality Among Stroke Patients in China

BACKGROUND AND OBJECTIVES

To characterize the association of ambient particulate matter (PM) pollution of different sizes (PM ≤1 µm in aerodynamic diameter [PM1], PM2.5, and PM10) with in-hospital case fatality among patients with stroke in China.

METHODS

We collected hospitalizations due to stroke in 4 provinces in China from 2013 to 2019. Seven-day and annual averages of PM prior to hospitalization were estimated using bilinear interpolation and residential addresses. Associations with in-hospital case fatality were estimated using random-effects logistic regression models. Potential reducible fraction and the number of fatalities attributed to PM were estimated using a counterfactual approach.

RESULTS

Among 3,109,634 stroke hospitalizations (mean age 67.23 years [SD 12.22]; 1,765,644 [56.78%] male), we identified 32,140 in-hospital stroke fatalities (case fatality rate 1.03%). Each 10 µg/m3 increase in 7-day average (short-term) exposure to PM was associated with increased in-hospital case fatality: odds ratios (ORs) were 1.058 (95% CI 1.047-1.068) for PM1, 1.037 (95% CI 1.031-1.043) for PM2.5, and 1.025 (95% CI 1.021-1.029) for PM10. Similar but larger ORs were observed for annual averages (long-term): 1.240 (95% CI 1.217-1.265) for PM1, 1.105 (95% CI 1.094-1.116) for PM2.5, and 1.090 (95% CI 1.082-1.099) for PM10. In counterfactual analyses, PM10 was associated with the largest potential reducible fraction in in-hospital case fatality (10% [95% CI 8.3-11.7] for short-term exposure and 21.1% [19.1%-23%] for long-term exposure), followed by PM1 and PM2.5.

DISCUSSION

PM pollution is a risk factor for in-hospital stroke-related deaths. Strategies that target reducing PM pollution may improve the health outcomes of patients with stroke.

Self-reported health condition severity and ambulation status postmajor dysvascular limb loss

BACKGROUND

Individuals with dysvascular lower limb amputations (LLA) secondary to complications of peripheral arterial disease (PAD) and/or diabetes have high rates of co-morbidities.

OBJECTIVES

To describe self-reported health condition severity and their association with sociodemographic factors and ambulations status among individuals with major dysvascular LLA.

STUDY DESIGN

Cross sectional telephone and in person survey with adults with major dysvascular LLA living in the community setting in Ontario, Canada.

METHODS

Survey by phone/in person, and completion of the Dysvascular Conditions Scale and Special Interest in Amputee Medicine Mobility (SIGAM) Grade by each participant.

RESULTS

Two hundred thirty-one individuals with major dysvascular LLAs participated in the study. Most of them were male individuals (80.5%) and had undergone a transtibial amputation (74%). On average, participants were 3.4 years postlimb loss and had five identified Dysvascular Conditions Scale health conditions. The top five reported health conditions were diabetes, hypertension, phantom limb pain, musculoskeletal pain, and back pain. With the exclusion of hypertension, these conditions were also perceived by respondents to be quite severe for their impact. Vision impairment was also rated as being severe in nature. Lower mobility Special Interest Group in Amputee Medicine grades were associated with higher health condition severity scores.

CONCLUSIONS

Individuals with dysvascular limb loss experience high multimorbidity with perceived negative impact on their overall wellness and function. Rehabilitation and self-management strategies to help patients with dysvascular LLAs to manage chronic health conditions may improve outcomes.

Geographic and Ethnic Inequalities in Diabetes-Related Amputations

Individuals with diabetes mellitus are at increasing risk for major lower-extremity amputations (LEAs). Poor quality of life and remarkable disabilities are associated with LEAs, determining a high economic burden for the healthcare systems. Reducing LEAs is therefore a primary marker of quality of care of the diabetic foot. At global level, between-countries comparisons of LEAs rates are basically hampered by differences in criteria used for data collection and analysis among studies. Significant variability in amputation rates exists between geographic areas, and also within specific regions of a country. Overall 5-year mortality rate after major amputations is reported to vary substantially across countries, from 50 to 80%. The odds of LEAs are substantially higher for Black, Native American and Hispanic ethnicities compared with White groups, with similar figures observed in the economically disadvantaged areas compared to more developed ones. Such discrepancies may reflect differences in diabetes prevalence as well as in financial resources, health-care system organization and management strategies of patients with diabetic foot ulcers. Looking at the experience of countries with lower rates of hospitalization and LEAs worldwide, a number of initiatives should be introduced to overcome these barriers. These include education and prevention programs for the early detection of diabetic foot at primary care levels, and the multidisciplinary team approach with established expertise in the treatment of the more advanced stage of disease. Such a coordinated system of support for both patients and physicians is highly required to reduce inequalities in the odd of diabetes-related amputations worldwide.

Risks of mental health outcomes in people with covid-19: cohort study

OBJECTIVE

To estimate the risks of incident mental health disorders in survivors of the acute phase of covid-19.

DESIGN

Cohort study.

SETTING

US Department of Veterans Affairs.

PARTICIPANTS

Cohort comprising 153 848 people who survived the first 30 days of SARS-CoV-2 infection, and two control groups: a contemporary group (n=5 637 840) with no evidence of SARS-CoV-2, and a historical control group (n=5 859 251) that predated the covid-19 pandemic.

MAIN OUTCOMES MEASURES

Risks of prespecified incident mental health outcomes, calculated as hazard ratio and absolute risk difference per 1000 people at one year, with corresponding 95% confidence intervals. Predefined covariates and algorithmically selected high dimensional covariates were used to balance the covid-19 and control groups through inverse weighting.

RESULTS

The covid-19 group showed an increased risk of incident anxiety disorders (hazard ratio 1.35 (95% confidence interval 1.30 to 1.39); risk difference 11.06 (95% confidence interval 9.64 to 12.53) per 1000 people at one year), depressive disorders (1.39 (1.34 to 1.43); 15.12 (13.38 to 16.91) per 1000 people at one year), stress and adjustment disorders (1.38 (1.34 to 1.43); 13.29 (11.71 to 14.92) per 1000 people at one year), and use of antidepressants (1.55 (1.50 to 1.60); 21.59 (19.63 to 23.60) per 1000 people at one year) and benzodiazepines (1.65 (1.58 to 1.72); 10.46 (9.37 to 11.61) per 1000 people at one year). The risk of incident opioid prescriptions also increased (1.76 (1.71 to 1.81); 35.90 (33.61 to 38.25) per 1000 people at one year), opioid use disorders (1.34 (1.21 to 1.48); 0.96 (0.59 to 1.37) per 1000 people at one year), and other (non-opioid) substance use disorders (1.20 (1.15 to 1.26); 4.34 (3.22 to 5.51) per 1000 people at one year). The covid-19 group also showed an increased risk of incident neurocognitive decline (1.80 (1.72 to 1.89); 10.75 (9.65 to 11.91) per 1000 people at one year) and sleep disorders (1.41 (1.38 to 1.45); 23.80 (21.65 to 26.00) per 1000 people at one year). The risk of any incident mental health diagnosis or prescription was increased (1.60 (1.55 to 1.66); 64.38 (58.90 to 70.01) per 1000 people at one year). The risks of examined outcomes were increased even among people who were not admitted to hospital and were highest among those who were admitted to hospital during the acute phase of covid-19. Results were consistent with those in the historical control group. The risk of incident mental health disorders was consistently higher in the covid-19 group in comparisons of people with covid-19 not admitted to hospital versus those not admitted to hospital for seasonal influenza, admitted to hospital with covid-19 versus admitted to hospital with seasonal influenza, and admitted to hospital with covid-19 versus admitted to hospital for any other cause.

CONCLUSIONS

The findings suggest that people who survive the acute phase of covid-19 are at increased risk of an array of incident mental health disorders. Tackling mental health disorders among survivors of covid-19 should be a priority.

Current Predictors of Mortality in Veteran Patients Undergoing Major Lower Extremity Amputations: Risk Factors Have Not Changed and Mortality Remains High

Major lower extremity amputation (LEA-above the ankle) carries a high rate of mortality. In the present study, we performed an institutional review of all patients submitting to LEAs at a Veteran Administration Hospital (between 2009 and 2021) accompanied with a review of the literature.For the past 12 years, 1042 LEAs were performed in 603 patients at our hospital. The 30-day, 1-year, and 5-year mortalities were 8.5%, 28.9%, and 53.0%, respectively. Age, hypoalbuminemia, and Clavien-Dindo Class were independent predictors of mortality in all the time intervals in the analysis. Cardiac disease was not an independent predictor of mortality. In 39 studies reviewed, the average 30-day, 1-year, and 5-year mortality was 14%, 36%, and 56%, respectively. There was no difference in mortality in multiple studies analyzed. No significant temporal variation was identified between 1950 and 2000 vs. 2001 and 2021. Predictors of mortality were not substantially different from our institutional experience.The mortality rate for LEAs remains constant over time. Increasing age and hypoalbuminemia are strong predictors of short- and long-term mortality.

Comparison of Rates of Lower Extremity Amputation in Patients With and Without Gout in the US Department of Veterans Affairs Health System

Importance

Cardiometabolic and other risk factors could render patients with gout more likely to undergo lower extremity amputation (LEA).

Objective

To examine the rate of and factors associated with LEA in patients with gout.

Design, Setting, and Participants

In this matched cohort study using national administrative data, multivariable Cox proportional hazards regression models were used to examine the associations of gout with LEA. In analyses limited to patients with gout, attributes of serum urate control and treatment with urate-lowering therapy were examined as factors associated with LEA. This study included patients who used US Department of Veterans Affairs services from January 1, 2000, to July 31, 2015. Patients with gout were identified using diagnostic codes and matched with up to 10 controls by age, sex, and year of benefit enrollment. Data analysis was performed from January 26, 2021, to September 3, 2021.

Exposures

Gout classification served as the primary independent variable of interest. In analyses limited to patients with gout, factors associated with serum urate control and urate-lowering therapy were examined.

Main Outcomes and Measures

Overall LEA, as well as toe, transmetatarsal, below-the-knee, and above-the-knee amputation.

Results

This cohort study included 5 924 918 patients, 556 521 with gout (mean [SD] age, 67 [12] years; 550 963 (99.0%) male; 88 853 [16.0%] Black non-Hispanic; 16 981 [4.3%] Hispanic/Latinx; 345 818 [62.1%] White non-Hispanic; 80 929 [14.5%] with race and ethnicity data missing; and 23 940 [4.3%] classified as other) and 5 368 397 without gout (mean [SD] age, 67 [12] years; 5 314 344 [99.0%] male; 558 464 [10.4%] Black non-Hispanic; 204 291 [3.0%] Hispanic/Latinx; 3 188 504 [59.4%] White non-Hispanic; 1 257 739 [23.4%)] with race and ethnicity data missing; and 159 399 [3.0%] classified as other). Compared with patients without gout, patients with gout were more likely to undergo amputation, an increased rate that remained after adjustment (adjusted hazard ratio, 1.20; 95% CI, 1.16-1.24) and was highest for below-the-knee amputation (adjusted hazard ratio, 1.59; 95% CI, 1.39-1.81). In those with gout, poor serum urate control (mean >7 mg/dL during the preceding year) was associated with a 25% to 37% increase in the rate of amputation. In contrast, treatment with urate-lowering therapy was not associated with the LEA rate.

Conclusions and Relevance

In this matched cohort study, patients with gout were more likely to undergo LEA. This increase was independent of other comorbidities that have been associated with amputation, including diabetes and peripheral vascular disease. Serum urate control was independently associated with the LEA rate, suggesting the possibility that lower extremity amputation may be preventable in some patients.

Interpreting global trends in type 2 diabetes complications and mortality

International trends in traditional diabetes complications (cardiovascular, renal, peripheral vascular, ophthalmic, hepatic or neurological diseases) and mortality rates are poorly characterised. An earlier review of studies published up to 2015 demonstrated that most data come from a dozen high-income countries (HICs) in North America, Europe or the Asia-Pacific region and that, in these countries at least, rates of acute glycaemic fluctuations needing medical attention and amputations, myocardial infarction and mortality were all declining over the period. Here, we provide an updated review of published literature on trends in type 2 diabetes complications and mortality in adults since 2015. We also discuss issues related to data collection, analysis and reporting that have influenced global trends in type 2 diabetes and its complications. We found that most data on trends in type 2 diabetes, its complications and mortality come from a small number of HICs with comprehensive surveillance systems, though at least some low- and middle-income countries (LMICs) from Africa and Latin America are represented in this review. The published data suggest that HICs have experienced declines in cardiovascular complication rates and all-cause mortality in people with diabetes. In parallel, cardiovascular complications and mortality rates in people with diabetes have increased over time in LMICs. However, caution is warranted in interpreting trends from LMICs due to extremely sparse data or data that are not comparable across countries. We noted that approaches to case ascertainment and definitions of complications and mortality (numerators) and type 2 diabetes (the denominator) vary widely and influence the interpretation of international data. We offer four key recommendations to more rigorously document trends in rates of type 2 diabetes complications and mortality, over time and worldwide: (1) increasing investments in data collection systems; (2) standardising case definitions and approaches to ascertainment; (3) strengthening analytical capacity; and (4) developing and implementing structured guidelines for reporting of data.

Size-Specific Particulate Matter Associated With Acute Lower Respiratory Infection Outpatient Visits in Children: A Counterfactual Analysis in Guangzhou, China

The burden of lower respiratory infections is primarily evident in the developing countries. However, the association between size-specific particulate matter and acute lower respiratory infection (ALRI) outpatient visits in the developing countries has been less studied. We obtained data on ALRI outpatient visits (N = 105,639) from a tertiary hospital in Guangzhou, China between 2013 and 2019. Over-dispersed generalized additive Poisson models were employed to evaluate the excess risk (ER) associated with the size-specific particulate matter, such as inhalable particulate matter (PM₁₀), coarse particulate matter (PM_c), and fine particulate matter (PM_2.5). Counterfactual analyses were used to examine the potential percent reduction of ALRI outpatient visits if the levels of air pollution recommended by the WHO were followed. There were 35,310 pneumonia, 68,218 bronchiolitis, and 2,111 asthma outpatient visits included. Each 10 μg/m³ increase of 3-day moving averages of particulate matter was associated with a significant ER (95% CI) of outpatient visits of pneumonia (PM_2.5: 3.71% [2.91, 4.52%]; PM_c: 9.19% [6.94, 11.49%]; PM₁₀: 4.36% [3.21, 5.52%]), bronchiolitis (PM_2.5: 3.21% [2.49, 3.93%]; PM_c: 9.13% [7.09, 11.21%]; PM₁₀: 3.12% [2.10, 4.15%]), and asthma (PM_2.5: 3.45% [1.18, 5.78%]; PM_c: 11.69% [4.45, 19.43%]; PM₁₀: 3.33% [0.26, 6.49%]). The association between particulate matter and pneumonia outpatient visits was more evident in men patients and in the cold seasons. Counterfactual analyses showed that PM_2.5 was associated with a larger potential decline of ALRI outpatient visits compared with PM_c and PM₁₀ (pneumonia: 11.07%, 95% CI: [7.99, 14.30%]; bronchiolitis: 6.30% [4.17, 8.53%]; asthma: 8.14% [2.65, 14.33%]) if the air pollutants were diminished to the level of the reference guidelines. In conclusion, short-term exposures to PM_2.5, PM_c, and PM₁₀ are associated with ALRI outpatient visits, and PM_2.5 is associated with the highest potential decline in outpatient visits if it could be reduced to the levels recommended by the WHO.

Burdens of post-acute sequelae of COVID-19 by severity of acute infection, demographics and health status

The Post-Acute Sequelae of SARS-CoV-2 infection (PASC) have been characterized; however, the burden of PASC remains unknown. Here we used the healthcare databases of the US Department of Veterans Affairs to build a cohort of 181,384 people with COVID-19 and 4,397,509 non-infected controls and estimated that burden of PASC-defined as the presence of at least one sequela in excess of non-infected controls-was 73.43 (72.10, 74.72) per 1000 persons at 6 months. Burdens of individual sequelae varied by demographic groups (age, race, and sex) but were consistently higher in people with poorer baseline health and in those with more severe acute infection. In sum, the burden of PASC is substantial; PASC is non-monolithic with sequelae that are differentially expressed in various population groups. Collectively, our results may be useful in informing health systems capacity planning and care strategies of people with PASC.

Ambient fine particulate matter air pollution and the risk of hospitalization among COVID-19 positive individuals: Cohort study

BACKGROUND

Ecologic analyses suggest that living in areas with higher levels of ambient fine particulate matter air pollution (PM2.5) is associated with higher risk of adverse COVID-19 outcomes. Studies accounting for individual-level health characteristics are lacking.

METHODS

We leveraged the breadth and depth of the US Department of Veterans Affairs national healthcare databases and built a national cohort of 169,102 COVID-19 positive United States Veterans, enrolled between March 2, 2020 and January 31, 2021, and followed them through February 15, 2021. Annual average 2018 PM2.5 exposure, at an approximately 1 km2 resolution, was linked with residential street address at the year prior to COVID-19 positive test. COVID-19 hospitalization was defined as first hospital admission between 7 days prior to, and 15 days after, the first COVID-19 positive date. Adjusted Poisson regression assessed the association of PM2.5 with risk of hospitalization.

RESULTS

There were 25,422 (15.0%) hospitalizations; 5,448 (11.9%), 5,056 (13.0%), 7,159 (16.1%), and 7,759 (19.4%) were in the lowest to highest PM2.5 quartile, respectively. In models adjusted for State, demographic and behavioral factors, contextual characteristics, and characteristics of the pandemic a one interquartile range increase in PM2.5 (1.9 µg/m3) was associated with a 10% (95% CI: 8%-12%) increase in risk of hospitalization. The association of PM2.5 and risk of hospitalization among COVID-19 individuals was present in each wave of the pandemic. Models of non-linear exposure-response suggested increased risk at PM2.5 concentrations below the national standard 12 µg/m3. Formal effect modification analyses suggested higher risk of hospitalization associated with PM2.5 in Black people compared to White people (p = 0.045), and in those living in socioeconomically disadvantaged neighborhoods (p < 0.001).

CONCLUSIONS

Exposure to higher levels of PM2.5 was associated with increased risk of hospitalization among COVID-19 infected individuals. The risk was evident at PM2.5 levels below the regulatory standards. The analysis identified those of Black race and those living in disadvantaged neighborhoods as population groups that may be more susceptible to the untoward effect of PM2.5 on risk of hospitalization in the setting of COVID-19.

Temporal trends of COVID-19 mortality and hospitalisation rates: an observational cohort study from the US Department of Veterans Affairs

OBJECTIVES

To investigate the temporal trends of 30-day mortality and hospitalisation in US Veterans with COVID-19 and 30-day mortality in hospitalised veterans with COVID-19 and to decompose the contribution of changes in the underlying characteristics of affected populations to these temporal changes.

DESIGN

Observational cohort study.

SETTING

US Department of Veterans Affairs.

PARTICIPANTS

49 238 US veterans with a positive COVID-19 test between 20 March 2020 and 19 September 2020; and 9428 US veterans hospitalised with a positive COVID-19 test during the same period.

OUTCOME MEASURES

30-day mortality rate and hospitalisation rate.

RESULTS

Between 20 March 2020 and 19 September 2020 and in COVID-19 positive individuals, 30-day mortality rate dropped by 9.2% from 13.6% to 4.4%; hospitalisation rate dropped by 16.8% from 33.8% to 17.0%. In hospitalised COVID-19 individuals, 30-day mortality rate dropped by 12.7% from 23.5% to 10.8%. Among COVID-19 positive individuals, decomposition analyses suggested that changes in demographic, health and contextual characteristics, COVID-19 testing capacity, and hospital occupancy rates accounted for 40.2% and 33.3% of the decline in 30-day mortality and hospitalisation, respectively. Changes in the underlying characteristics of hospitalised COVID-19 individuals accounted for 29.9% of the decline in 30-day mortality.

CONCLUSION

Between March and September 2020, changes in demographic and health characteristics of people infected with COVID-19 contributed measurably to the substantial decline in 30-day mortality and hospitalisation.

Epidemiology of Peripheral Artery Disease and Polyvascular Disease

Atherosclerotic lower extremity peripheral artery disease (PAD) is increasingly recognized as an important cause of cardiovascular morbidity and mortality that affects >230 million people worldwide. Traditional cardiovascular risk factors, including advanced age, smoking, and diabetes, are strongly linked to an increase risk of PAD. Although PAD has been historically underappreciated compared with coronary artery disease and stroke, greater attention on PAD in recent years has led to important new epidemiological insights in the areas of thrombosis, inflammation, dyslipidemia, and microvascular disease. In addition, the concept of polyvascular disease, or clinically evident atherosclerosis in multiple arterial beds, is increasingly identified as a particularly malignant cardiovascular disease worthy of special clinical attention and further study. It is noteworthy that PAD may increase the risk of adverse outcomes in similar or even greater magnitude than coronary disease or stroke. In this review, we highlight important new advances in the epidemiology of PAD with a particular focus on polyvascular disease, emerging biomarkers, and differential risk pathways for PAD compared with other atherosclerotic diseases.