Health care resources and costs for treating peripheral artery disease in a managed care population: results from analysis of administrative claims data

Identification and Evaluation of Blood-Based Biomarkers for Abdominal Aortic Aneurysm

INTRODUCTION

Blood-based biomarkers for abdominal aortic aneurysm (AAA) have been studied individually; however, we considered a panel of proteins to investigate AAA prognosis and its potential to improve predictive accuracy.

MATERIALS AND METHODS

Using a prospectively recruited cohort of patients with/without AAA (n = 452), we conducted a prognostic study to develop a model that accurately predicts AAA outcomes using clinical features and circulating biomarker levels. Serum concentrations of 9 biomarkers were measured at baseline, and the cohort was followed for 2 years. The primary outcome was major adverse aortic event (MAAE; composite of rapid AAA expansion [>0.5 cm/6 months or >1 cm/12 months], AAA intervention, or AAA rupture). Using 10-fold cross-validation, we trained a random forest model to predict 2 year MAAE using (1) clinical characteristics, (2) biomarkers, and (3) clinical characteristics and biomarkers.

RESULTS

Two-year MAAE occurred in 114 (25%) patients. Two proteins were significantly elevated in patients with AAA compared with those without AAA (angiopoietin-2 and aggrecan), composing the protein panel. For predicting 2 year MAAE, our random forest model achieved area under the receiver operating characteristic curve (AUROC) 0.74 using clinical features alone, and the addition of the 2-protein panel improved performance to AUROC 0.86.

CONCLUSIONS

Using a combination of clinical/biomarker data, we developed a model that accurately predicts 2 year MAAE.

A machine learning algorithm for peripheral artery disease prognosis using biomarker data

Peripheral artery disease (PAD) biomarkers have been studied in isolation; however, an algorithm that considers a protein panel to inform PAD prognosis may improve predictive accuracy. Biomarker-based prediction models were developed and evaluated using a model development (n = 270) and prospective validation cohort (n = 277). Plasma concentrations of 37 proteins were measured at baseline and the patients were followed for 2 years. The primary outcome was 2-year major adverse limb event (MALE; composite of vascular intervention or major amputation). Of the 37 proteins tested, 6 were differentially expressed in patients with vs. without PAD (ADAMTS13, ICAM-1, ANGPTL3, Alpha 1-microglobulin, GDF15, and endostatin). Using 10-fold cross-validation, we developed a random forest machine learning model that accurately predicts 2-year MALE in a prospective validation cohort of PAD patients using a 6-protein panel (AUROC 0.84). This algorithm can support PAD risk stratification, informing clinical decisions on further vascular evaluation and management.

Endovascular Interventions for Peripheral Arterial Disease in Saudi Patients: A Cross-Sectional Study Assessing Efficacy and Economic Impact

Introduction Peripheral Arterial Disease (PAD) is characterized by arterial narrowing or blockage, causing pain and reduced quality of life. Endovascular interventions, like angioplasty and stenting, offer less invasive treatment options with potential benefits. This study, conducted in the Al-Ahsa region of Saudi Arabia from January to August 2023, aims to assess the impact of these interventions on PAD management in Saudi patients. Specifically, we aim to evaluate their effectiveness in improving clinical outcomes, such as symptom relief and quality of life, and their cost-effectiveness in the Saudi healthcare system. By addressing these objectives, our research provides evidence to support informed clinical decisions and healthcare policy in Saudi Arabia, ultimately enhancing patient care. Methods In this study, a cross-sectional design was used to assess the impact of endovascular interventions on PAD management in Saudi patients in the Al-Ahsa region. Data collection took place from January to August 2023. The study focused on a sample of 385 or more Saudi patients who had undergone endovascular interventions. Inclusion criteria involved diagnosed PAD patients who had received these interventions, while non-Saudi patients and those without PAD or interventions were excluded. Data was collected through an online questionnaire distributed in hospitals. The study considered demographic and clinical/economic variables to evaluate intervention effectiveness and cost-effectiveness. Results The findings of this study emphasize the significance of variables such as gender, education level, employment status, and geographic location in shaping perceptions concerning the effectiveness and cost-effectiveness of endovascular interventions for the management of PAD. Participants in the study reported substantial improvements in symptom relief, quality of life, and daily activities following endovascular interventions. Moreover, the study revealed divergent perceptions regarding the cost-effectiveness of these interventions among participants. Conclusion This study highlights a positive association between the use of endovascular interventions and improved clinical outcomes in Saudi patients diagnosed with PAD. The results of this research indicate that endovascular interventions are not only more cost-effective when compared to alternative treatment modalities for PAD management but also lead to significant enhancements in symptom relief, quality of life, and daily activities among patients. The implications of these findings for the Saudi healthcare system are substantial, underscoring the importance of evidence-based decisions in the adoption of endovascular interventions for PAD management.

Clinical investigation of the GORE Drug-Coated PTA Balloon Catheter for CE Mark Approval

OBJECTIVES

Paclitaxel-coated balloon angioplasty has been established as the first-line therapy of femoropopliteal artery disease. The primary objectives of the study were to evaluate the performance and the safety of the GORE-DCB Catheter in the treatment of atherosclerotic femoropopliteal lesions of patients with peripheral artery disease for CE-Mark approval.

METHODS

Prospective, single-arm, multicenter study with 24 months follow-up. The GORE-DCB Catheter consists of a drug-coated nylon (inner layer)/ePTFE (outer layer) composite balloon. The ePTFE layer is coated with paclitaxel (concentration: 3.5μg/mm²), and the excipients stearic acid/tromethamine (tris). The primary endpoints were 6-month late lumen loss (LLL) and 30-day of freedom from Major Adverse Events (MAE).

RESULTS

Fifty-two subjects were enrolled, 69% men, median age 69 (49-83) years. Acute device success was 100%, the 30-day MAE rate was zero. Study primary endpoint of LLL (-0.17 mm) showed significant superiority compared to the performance goal of uncoated PTA balloon catheters from literature. At 1 and 2 years primary patency rates were 81.8% and 68.7%, respectively, and freedom from clinical driven target lesion revascularization rates were 87.9% and 83.4%, respectively.

CONCLUSION

The study demonstrates that the treatment of lesions in femoropopliteal arteries with the GORE-DCB Catheter is safe and effective.

Geographic Disparities in Readmissions for Peripheral Artery Disease in South Carolina

Readmissions constitute a major health care burden among peripheral artery disease (PAD) patients. This study aimed to 1) estimate the zip code tabulation area (ZCTA)-level prevalence of readmission among PAD patients and characterize the effect of covariates on readmissions; and (2) identify hotspots of PAD based on estimated prevalence of readmission. Thirty-day readmissions among PAD patients were identified from the South Carolina Revenue and Fiscal Affairs Office All Payers Database (2010-2018). Bayesian spatial hierarchical modeling was conducted to identify areas of high risk, while controlling for confounders. We mapped the estimated readmission rates and identified hotspots using local Getis Ord (G*) statistics. Of the 232,731 individuals admitted to a hospital or outpatient surgery facility with PAD diagnosis, 30,366 (13.1%) experienced an unplanned readmission to a hospital within 30 days. Fitted readmission rates ranged from 35.3 per 1000 patients to 370.7 per 1000 patients and the risk of having a readmission was significantly associated with the percentage of patients who are 65 and older (0.992, 95%CI: 0.985-0.999), have Medicare insurance (1.013, 1.005-1.020), and have hypertension (1.014, 1.005-1.023). Geographic analysis found significant variation in readmission rates across the state and identified priority areas for targeted interventions to reduce readmissions.

Midlife Cardiorespiratory Fitness and the Development of Peripheral Artery Disease in Later Life

Background Data are sparse on the prospective associations between physical activity and incidence of lower extremity peripheral artery disease (PAD). Methods and Results Linking participant data from the CCLS (Cooper Center Longitudinal Study) to Medicare claims files, we studied 19 023 participants with objectively measured midlife cardiorespiratory fitness through maximal effort on the Balke protocol who survived to receive Medicare coverage between 1999 and 2009. The study aimed to determine the association between midlife cardiorespiratory fitness and incident PAD with proportional hazards intensity models, adjusted for age, sex, body mass index, and other covariates, to PAD failure time data. During 121 288 person-years of Medicare follow-up, we observed 805 PAD-related hospitalizations/procedures among 19 023 participants (21% women, median age 50 years). Lower midlife fitness was associated with a higher rate of incident PAD in patients aged 65 years and older (low fit [quintile 1]: 11.4, moderate fit [quintile 2 to 3]: 7.8, and high fit [quintile 4 to 5]: 5.7 per 1000 person years). After multivariable adjustment for common predictors of incident PAD such as age, body mass index, hypertension, and diabetes, these findings persisted. Lower risk for PAD per greater metabolic equivalent task of fitness was observed (hazard ratio [HR], 0.93 [95% CI, 0.90-0.97]; P<0.001). Among a subset of patients with an additional fitness assessment, each 1 metabolic equivalent task increase from baseline fitness was associated with decreased risk of incident PAD (HR, 0.90 [95% CI, 0.82-0.99]; P=0.03). Conclusions Cardiorespiratory fitness in healthy, middle-aged adults is associated with lower risk of incident PAD in later life, independent of other predictors of incident PAD.

Variability in utilization of diagnostic imaging tests in patients with symptomatic peripheral artery disease

AIM

Imaging can help guide management in peripheral arterial disease (PAD) with symptoms refractory to medical treatment. However, there are no set guidelines to determine when physicians should seek further imaging in patients with PAD for the assessment of new, persistent or worsening symptoms. This study describes the rates and variability in non-invasive and invasive imaging for patients presenting to vascular specialty clinics for symptomatic PAD.

METHODS

Patients (n=1,275) with a new PAD diagnosis or exacerbation of PAD symptoms were enrolled from 16 vascular clinics. Hierarchical logistic regression models were used to estimate the referral rates for 1) non-invasive and 2) invasive imaging tests, after adjusting for patient demographics, disease characteristics, PAQ summary score, PAD performance measures and country. Median Odds Ratios (MOR) were calculated to examine the variability across sites and providers.

RESULTS

Mean ABI was 0.67 ± 0.19. There were 690 (54.1%) patients who had imaging, of which 62 (9.0%) had invasive imaging. Imaging rates ranged from 8.6% to 98.6% across sites. The MOR for use of imaging for site was 3.36 (p < 0.001) and provider 3.49 (p < 0.001). The variability was explained primarily by (R² = 29%) country followed by patient-level factors, provider and lastly site (R² = 17%, 14%, and 13%, respectively).

CONCLUSION

There is wide variation in the use of imaging for patients presenting with new onset or recent exacerbations of their PAD. Country, followed by provider and site, were most strongly associated with this variability after adjusting for patient characteristics.

Recent Developments in Ozone Sensor Technology for Medical Applications

There is increasing interest in the utilisation of medical gases, such as ozone, for the treatment of herniated disks, peripheral artery diseases, and chronic wounds, and for dentistry. Currently, the in situ measurement of the dissolved ozone concentration during the medical procedures in human bodily liquids and tissues is not possible. Further research is necessary to enable the integration of ozone sensors in medical and bioanalytical devices. In the present review, we report selected recent developments in ozone sensor technology (2016–2020). The sensors are subdivided into ozone gas sensors and dissolved ozone sensors. The focus thereby lies upon amperometric and impedimetric as well as optical measurement methods. The progress made in various areas—such as measurement temperature, measurement range, response time, and recovery time—is presented. As inkjet-printing is a new promising technology for embedding sensors in medical and bioanalytical devices, the present review includes a brief overview of the current approaches of inkjet-printed ozone sensors.

Economic burden of coronary artery disease or peripheral artery disease in patients at high risk of ischemic events in the French setting: a claims database analysis

Aims: Estimate the direct costs of high-risk patients presenting with coronary artery disease (CAD) or peripheral artery disease (PAD) in France.Materials and methods: This retrospective cohort study used a representative claims database, the "Echantillon Généraliste de Bénéficiaires" (EGB), to identify patients presenting with CAD or PAD between 2011 and 2016. Among those, patients meeting the COMPASS trial selection criteria were selected, as well as controls matched on age and sex. Direct costs (Euros 2016) were estimated in a societal perspective by comparing case and controls.Results: The adult population presenting with CAD or PAD in the EGB in 2016 was estimated at 29,888 individuals, representing a crude prevalence rate of 5.44%. After using the documented selection criteria of the COMPASS study, this population (COMPASS-like) was estimated at 17,369 individuals (58.1% of the CAD and/or PAD total population). Among them, a proportion of 11.5% presented with CAD + PAD. Compared with the original COMPASS population, patients were older (76.5 vs 68.2 years) and with a lower male predominance (60.0% vs 78.2% males). Compared with controls, the COMPASS-like population was characterized by a higher annual mortality (5.9% vs 3.5%) and the presence of more comorbidities on top of CAD and/or PAD. The annual per capita extra direct cost of the COMPASS-like population was estimated at €4,284, with a main contribution from inpatient care (58.9%). This extra cost was higher in the PAD ± CAD sub-group (€5,552) and the CAD + PAD sub-group (€8,067).Limitations: The EGB had limitations about several clinical features defining high-risk patients that may lead to bias in our estimates.Conclusions: Due to the high prevalence of CAD and/or PAD and the associated high unit costs, this population generates a significant economic burden, which is higher among patients with PAD and in those presenting simultaneously with both conditions.

Imaging the Landmarks of Vascular Recovery

Background: Peripheral arterial disease (PAD) is a major worldwide health concern. Since the late 1990s therapeutic angiogenesis has been investigated as an alternative to traditional PAD treatments. Although positive preclinical results abound in the literature, the outcomes of human clinical trials have been discouraging. Among the challenges the field has faced has been a lack of standardization of the timings and measures used to validate new treatment approaches.

Methods: In order to study the spatiotemporal dynamics of both perfusion and neovascularization in mice subjected to surgically-induced hindlimb ischemia (n= 30), we employed three label-free imaging modalities (a novel high-sensitivity ultrasonic Power Doppler methodology, laser speckle contrast, and photoacoustic imaging), as well as a tandem of radio-labeled molecular probes, ^99mTc-NC100692 and ^99mTc-BRU-5921 respectively, designed to detect two key modulators of angiogenic activity, α_Vβ₃ and HIF-1α , via scintigraphic imaging.

Results: The multimodal imaging strategy reveals a set of “landmarks”—key physiological and molecular events in the healing process—that can serve as a standardized framework for describing the impact of emerging PAD treatments. These landmarks span the entire process of neovascularization, beginning with the rapid decreases in perfusion and oxygenation associated with ligation surgery, extending through pro-angiogenic changes in gene expression driven by the master regulator HIF-1α , and ultimately leading to complete functional revascularization of the affected tissues.

Conclusions: This study represents an important step in the development of multimodal non-invasive imaging strategies for vascular research; the combined results offer more insight than can be gleaned through any of the individual imaging methods alone. Researchers adopting similar imaging strategies and will be better able to describe changes in the onset, duration, and strength of each of the landmarks of vascular recovery, yielding greater biological insight, and enabling more comprehensive cross-study comparisons. Perhaps most important, this study paves the road for more efficient translation of PAD research; emerging experimental treatments can be more effectively assessed and refined at the preclinical stage, ultimately leading to better next-generation therapies.

Evaluation of machine learning methodology for the prediction of healthcare resource utilization and healthcare costs in patients with critical limb ischemia-is preventive and personalized approach on the horizon?

Background

Critical limb ischemia (CLI) is a severe stage of peripheral arterial disease and has a substantial disease and economic burden not only to patients and families, but also to the society and healthcare systems. We aim to develop a personalized prediction model that utilizes baseline patient characteristics prior to CLI diagnosis to predict subsequent 1-year all-cause hospitalizations and total annual healthcare cost, using a novel Bayesian machine learning platform, Reverse Engineering Forward Simulation™ (REFS™), to support a paradigm shift from reactive healthcare to Predictive Preventive and Personalized Medicine (PPPM)-driven healthcare.

Methods

Patients ≥ 50 years with CLI plus clinical activity for a 6-month pre-index and a 12-month post-index period or death during the post-index period were included in this retrospective cohort of the linked Optum-Humedica databases. REFS™ built an ensemble of 256 predictive models to identify predictors of all-cause hospitalizations and total annual all-cause healthcare costs during the 12-month post-index interval.

Results

The mean age of 3189 eligible patients was 71.9 years. The most common CLI-related comorbidities were hypertension (79.5%), dyslipidemia (61.4%), coronary atherosclerosis and other heart disease (42.3%), and type 2 diabetes (39.2%). Post-index CLI-related healthcare utilization included inpatient services (14.6%) and ≥ 1 outpatient visits (32.1%). Median annual all-cause and CLI-related costs per patient were $30,514 and $2196, respectively. REFS™ identified diagnosis of skin and subcutaneous tissue infections, cellulitis and abscess, use of nonselective beta-blockers, other aftercare, and osteoarthritis as high confidence predictors of all-cause hospitalizations. The leading predictors for total all-cause costs included region of residence and comorbid health conditions including other diseases of kidney and ureters, blindness of vision defects, chronic ulcer of skin, and chronic ulcer of leg or foot.

Conclusions

REFS™ identified baseline predictors of subsequent healthcare resource utilization and costs in CLI patients. Machine learning and model-based, data-driven medicine may complement physicians' evidence-based medical services. These findings also support the PPPM framework that a paradigm shift from post-diagnosis disease care to early management of comorbidities and targeted prevention is warranted to deliver a cost-effective medical services and desirable healthcare economy.

A Targeted Literature Review of the Disease Burden in Patients With Symptomatic Peripheral Artery Disease

Patients with peripheral artery disease (PAD) have an increased risk of cardiovascular (CV) and limb events, but the disease is frequently underdiagnosed and treatment options are limited. This review examines the disease burden of symptomatic PAD as well as key guideline recommendations. Publications were identified using the ProQuest portal to access the Medline, Medline In-Process, and Embase databases. Search terms for symptomatic PAD were combined with terms relevant to epidemiology, burden, treatment practice, and physiopathology. Articles in English published between January 2001 and September 2016 were screened according to the population, interventions, comparator, outcomes, and study design criteria. Relevant publications (n = 200) were identified. The reported incidence and prevalence of PAD varied depending on the definitions used and the study populations. Patients generally had a poor prognosis, with an increased risk of mortality, CV, and limb events and decreased quality of life. Guideline recommendations included ankle–brachial index measurements, exercise testing, and angiography for diagnosis and risk factor modification, antiplatelets, cilostazol, exercise therapy, or surgical interventions for treatment, depending on the patient profile. The clinical, humanistic, and economic burden of disease in patients with symptomatic PAD is substantial and needs to be reduced through improved PAD management.

Extracorporeal shock wave-assisted adipose-derived fresh stromal vascular fraction restores the blood flow of critical limb ischemia in rat

We tested the hypothesis that extracorporeal-shock-wave (ECSW)-assisted adipose-derived stromal vascular fraction (SVF) therapy was better than either one for restoring the blood flow in critical limb ischemia (CLI). Adult male-SD rats were categorized into group 1 (sham-operated-control), group 2 (CLI), group 3 [CLI + ECSW (280 impulses/0.10 mJ/mm²) applied to left inguinal area at 3 h after CLI], group 4 [CLI + SVF (1.2 × 10⁶) implanted into CLI area at 3 h after CLI], group 5 (CLI + ECSW-SVF). In vitro studies showed that ECSW significantly enhanced angiogenesis in human umbilical-vein endothelial cells and carotid-artery ring, and SVF significantly suppressed inflammation (TNF-α/NF-Κb/IL-1ß/MMP-9) in smooth-muscle cells treated by LPS (all p < .001). By day 14 after CLI, the ratio of ischemic/normal blood flow (INBF) was highest in group 1, lowest in group 2, significantly higher in group 5 than in groups 3 and 4, but no difference was shown between the latter two groups (all p < .001). The fibrotic area in CLI region exhibited an opposite pattern of INBF ratio (all p < .0001). Protein (CD31/vWF/eNOS) and cellular (CD31/vWF) expressions and number of small vessels in CLI area exhibited an identical pattern, whilst protein expressions of apoptotic (caspase3/PARP/mitochondrial-Bax) fibrotic/DNA-damaged (Samd3/TFG-ß/γ-H2AX) biomarkers exhibited an opposite pattern to INBF among five groups (all p < .0001). The numbers of angiogenetic cells in CLI region (SDF-1α/VEGF/CXCR4) and endothelial-progenitor cells (C-kit/CD31+//Sca-1/CD31+//CD34/KDR+/VE-cadherin/CD34+) in circulation significantly and progressively increased from groups 2 to 5 (all p < .0001). In conclusion, ECSW-SVF therapy effectively enhanced angiogenesis and restoration of blood flow in CLI area.

Radiation dose and image quality with new protocol in lower extremity computed tomography angiography

PURPOSE

To compare radiation dose and image quality of lower extremity computed tomography angiography (CTA) between cranio-caudal acquisition with single-source CT (SSCT) and flash caudo-cranial acquisition with dual-source CT (DSCT).

MATERIALS AND METHODS

In this prospective study, 60 patients were randomly assigned to Group A (control) or Group B (experimental) to undergo lower extremity CTA for peripheral obliterative arterial disease. Group A received protocol 1 (P1) with SSCT cranio-caudal acquisition. Group B received protocol (P2) with DSCT flash caudo-cranial acquisition. Intravascular attenuation (IVA), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and image noise were compared. Two radiologists assessed the image quality. Computed tomography volume dose index (CTDI_vol) and dose-length product (DLP) were also compared.

RESULTS

IVA with P2 was higher than with P1 (586.8 ± 140.3 vs. 496.1 ± 129.3 HU, p = 0.011), as was SNR (33.0 ± 11.3 vs. 27.4 ± 12.3; p = 0.042), CNR (30.1 ± 13.3 vs. 24.2 ± 10.3; p = 0.029) and image quality score of small arteries below the knee (3.8 ± 0.2 vs. 3.1 ± 0.2; p = 0.001). Radiation dose was significantly lower in P2 than in P1 with CTDI_vol reduction of 40.9% (1.3 ± 0.1 vs. 2.2 ± 0.3 mGy; p = 0.006) and DLP reduction of 42.8% (148.7 ± 21.9 vs 260.2 ± 59.1 mGy * cm; p = 0.018).

CONCLUSION

Lower extremity CTA with DSCT flash caudo-cranial acquisition allows lower radiation dose with higher IVA, SNR, CNR and better image quality for small arteries below the knee than SSCT cranio-caudal acquisition.

Association of Human Immunodeficiency Virus Infection and Risk of Peripheral Artery Disease

BACKGROUND

The effect of human immunodeficiency virus (HIV) on the development of peripheral artery disease (PAD) remains unclear. We investigated whether HIV infection is associated with an increased risk of PAD after adjustment for traditional atherosclerotic risk factors in a large cohort of HIV-infected (HIV+) and demographically similar HIV-uninfected veterans.

METHODS

We studied participants in the Veterans Aging Cohort Study from April 1, 2003 through December 31, 2014. We excluded participants with known prior PAD or prevalent cardiovascular disease (myocardial infarction, stroke, coronary heart disease, and congestive heart failure) and analyzed the effect of HIV status on the risk of incident PAD events after adjusting for demographics, PAD risk factors, substance use, CD4 cell count, HIV-1 ribonucleic acid, and antiretroviral therapy. The primary outcome is incident peripheral artery disease events. Secondary outcomes include mortality and amputation in subjects with incident PAD events by HIV infection status, viral load, and CD4 count.

RESULTS

Among 91 953 participants, over a median follow up of 9.0 years, there were 7708 incident PAD events. Rates of incident PAD events per 1000 person-years were higher among HIV+ (11.9; 95% confidence interval [CI], 11.5-12.4) than uninfected veterans (9.9; 95% CI, 9.6-10.1). After adjustment for demographics, PAD risk factors, and other covariates, HIV+ veterans had an increased risk of incident PAD events compared with uninfected veterans (hazard ratio [HR], 1.19; 95% CI, 1.13-1.25). This risk was highest among those with time-updated HIV viral load >500 copies/mL (HR, 1.51; 95% CI, 1.38-1.65) and CD4 cell counts <200 cells/mm³ (HR, 1.91; 95% CI, 1.71-2.13). In contrast, HIV+ veterans with time updated CD4 cell count ≥500 cells/mm³ had no increased risk of PAD (HR, 1.03; 95% CI, 0.96-1.11). Mortality rates after incident PAD events are high regardless of HIV status. HIV infection did not affect rates of amputation after incident PAD events.

CONCLUSIONS

Infection with HIV is associated with a 19% increased risk of PAD beyond that explained by traditional atherosclerotic risk factors. However, for those with sustained CD4 cell counts <200 cells/mm³, the risk of incident PAD events is nearly 2-fold higher whereas for those with sustained CD4 cell counts ≥500 cells/mm³ there is no excess risk of incident PAD events compared with uninfected people.

The Evolving Treatment of Peripheral Arterial Disease through Guideline-Directed Recommendations

Peripheral arterial disease (PAD) refers to partial or complete occlusion of one or more non-coronary arteries that leads to compromised blood flow and ischemia. Numerous processes are involved in arterial stenosis, however, atherosclerosis remains the most common etiology. PAD constitutes a major health economic problem, and it is estimated that over 200 million people around the world suffer from PAD, with at least 20% having some degree of claudication. The purpose of this review is to compare and contrast the guidelines on PAD published in 2005, 2011 and 2016 in terms of new recommendations and level of evidence for practicing clinicians.

Cost-effectiveness analysis of drug-coated therapies in the superficial femoral artery

OBJECTIVE

Drug-coated balloons (DCBs) may increase durability of endovascular treatment of superficial femoral artery (SFA) disease while avoiding stent-related risks. The purpose of this study was to use meta-analytic data of DCB studies to compare the cost-effectiveness of potential SFA treatments: DCB, drug-eluting stent (DES), plain old balloon angioplasty (POBA), or bare-metal stent (BMS).

METHODS

A search for randomized controlled trials comparing DCB with POBA for treatment of SFA disease was performed. Hazard ratios were extracted to account for the time-to-event primary outcome of target lesion revascularization. Odds ratios were calculated for the secondary outcomes of primary patency (PP) and major amputation. Incorporating pooled data from the meta-analysis, cost-effectiveness analysis, assuming a payer perspective, used a decision model to simulate patency at 1 year and 2 years for each index treatment modality: POBA, BMS, DCB, or DES. Costs were based on current Medicare outpatient reimbursement rates.

RESULTS

Eight studies (1352 patients) met inclusion criteria for meta-analysis. DCB outperformed POBA with respect to target lesion revascularization over time (pooled hazard ratio, 0.41; P < .001). Risk of major amputation at 12 months was not significantly different between groups. There was significantly improved 1-year PP in the DCB group compared with POBA (pooled odds ratio, 3.30; P < .001). In the decision model, the highest PP at 1 year was seen in the DES index therapy strategy (79%), followed by DCB (74%), BMS (71%), and POBA (64%). With a baseline cost of $9259.39 per patent limb at 1 year in the POBA-first group, the incremental cost per patent limb for each other strategy compared with POBA was calculated: $14,136.10/additional patent limb for DCB, $38,549.80/limb for DES, and $59,748,85/limb for BMS. The primary BMS option is dominated by being more expensive and less effective than DCB. Compared directly with DCB, DES costs $87,377.20 per additional patent limb at 1 year. Based on the projected PP at 1 year in the decision model, the number needed to treat for DES compared with DCB is 20. At current reimbursement, the use of more than two DCBs per procedure would no longer be cost-effective compared with DES. At 2 years, DCB emerges as the most cost-effective index strategy with the lowest overall cost and highest patency rates over that time horizon.

CONCLUSIONS

Current data and reimbursements support the use of DCB as a cost-effective strategy for endovascular intervention in the SFA; any additional effectiveness of DES comes at a high price. Use of more than one DCB per intervention significantly decreases cost-effectiveness.

Underuse of Oral Anticoagulants and Inappropriate Prescription of Antiplatelet Therapy in Older Inpatients with Atrial Fibrillation

BACKGROUND

Several studies have shown that the prescription of antiplatelet therapy (APT) is associated with an increased risk of oral anticoagulant (OAC) underuse in patients aged 75 years and over with atrial fibrillation (AF). An associated atheromatous disease may be the underlying reason for APT prescription. The objective of the study was to determine whether the association between underuse of OAC and APT prescription was explained by the presence of an atheromatous disease.

METHODS AND RESULTS

We performed a retrospective, observational, single-centre study between 2009 and 2013 based on administrative data. Patients aged 75 years and over with non-valvular AF were identified in a database of 72,090 hospital stays. Prescriptions of anti-thrombotic medications and their association with the presence of atheromatous disease were evaluated by the mean of a logistic regression. A total of 2034 hospital stays were included (mean age 84.3 ± 5.2 years). The overall prevalence of known atheromatous disease was 25.9%. OAC underuse was observed in 58.5% of the stays. In multivariable analysis, the prescription of an APT was associated with an increased risk of OAC underuse [odds ratio (OR) 6.85; 95% confidence interval (CI) 5.50-8.58], independently of the presence of a concomitant known atheromatous disease (OR 0.78; 95% CI 0.60-1.01). Among the 692 stays with APT monotherapy (34.0%), 232 (33.5%) displayed an atheromatous disease.

CONCLUSIONS

The underuse of OAC is associated with the prescription of APT in older patients with AF, regardless of the presence or absence of known atheromatous disease. Our results suggest that APT is often inappropriately prescribed instead of OAC.

Peripheral Artery Disease Prevalence and Incidence Estimated From Both Outpatient and Inpatient Settings Among Medicare Fee-for-Service Beneficiaries in the Atherosclerosis Risk in Communities (ARIC) Study

Background

Outpatient ascertainment of peripheral artery disease (PAD) is rarely considered in the measurement of PAD clinical burden; therefore, the clinical burden of PAD likely has been underestimated while contributing to a decreased awareness of PAD in comparison to other circulatory system disorders.

Methods and Results

The purpose of this study was to estimate the age‐standardized annual period prevalence and incidence of PAD in the outpatient and inpatient settings using data from the Atherosclerosis Risk in Communities (ARIC) study linked with Centers for Medicare and Medicaid Services claims. The majority (>70%) of all PAD encounters occurred in the outpatient setting. The weighted mean age‐standardized prevalence and incidence of outpatient PAD was 11.8% (95% CI 11.5–12.1) and 22.4 per 1000 person‐years (95% CI 20.8–24.0), respectively. Black patients had higher weighted mean age‐standardized prevalence (15.6%; 95% CI 14.6–16.4) compared with white patients (11.4%; 95% CI 11.1–11.7). Black women had the highest weighted mean age‐standardized prevalence (16.9%; 95% CI 16.0–17.8). Black patients also had a higher incidence rate of PAD (31.3 per 1000 person‐years; 95% CI 27.3–35.4) compared with white patients (25.4 per 1000 person‐years; 95% CI 23.5–27.3). PAD prevalence and incidence did not differ by sex alone.

Conclusions

This study provides comprehensive estimates of PAD in the inpatient and outpatient settings where the majority of PAD burden was found. PAD is an important circulatory system disorder similar in prevalence to stroke and coronary heart disease.

Comparative Assessment of Medical Resource Use and Costs Associated with Patients with Symptomatic Peripheral Artery Disease in the United States

BACKGROUND

There is growing concern about appropriate disease management for peripheral artery disease (PAD) because of the rapidly expanding population at risk for PAD and the high burden of illness associated with symptomatic PAD. A better understanding of the potential economic impact of symptomatic PAD relative to a matched control population may help improve care management for these patients.

OBJECTIVE

To compare the medical resource utilization, costs, and medication use for patients with symptomatic PAD relative to a matched control population.

METHODS

In this retrospective longitudinal analysis, the index date was the earliest date of a symptomatic PAD record (symptomatic PAD cohort) or any medical record (control cohort), and a period of 1 year pre-index and 3 years post-index was the study time frame. Symptomatic PAD patients and control patients (aged ≥ 18 years) enrolled in the MarketScan Commercial and Encounters database from January 1, 2006, to June 30, 2010, were identified. Symptomatic PAD was defined as having evidence of intermittent claudication (IC) and/or acute critical limb ischemia requiring medical intervention. Symptomatic PAD patients were selected using an algorithm comprising a combination of PAD-related ICD-9-CM diagnostic and diagnosis-related group codes, peripheral revascularization CPT-4 procedure codes, and IC medication National Drug Code numbers. Patients with stroke/transient ischemic attack, bleeding complications, or contraindications to antiplatelet therapy were excluded from the symptomatic PAD group but not the control group. A final 1:1 symptomatic PAD to control population with an exact match based on age, sex, index year, and Charlson Comorbidity Index (CCI) was identified. Descriptive statistics comparing patient demographics, comorbidities, medical resource utilization, cost, and medication use outcomes were generated. Generalized linear models were developed to compare the outcomes while controlling for residual difference in demographics, comorbidities, pre-index resource use, and pre-index costs.

RESULTS

3,965 symptomatic PAD and 3,965 control patients were matched. In both cohorts, 54.7% were male, with a mean age (SD) of 69.0 (12.9) years and a CCI score of 1.3 (0.9). Symptomatic PAD patients had more cardiovascular comorbidities than control patients (27.7% vs. 12.6% coronary artery disease, 27.1% vs. 15.9% hyperlipidemia, and 49.8% vs. 28.2% hypertension) in the pre-index period. Post-index rates of ischemic stroke, non-ST segment elevation myocardial infarction, unstable angina, and cardiovascular- or PAD-related procedures (limb amputations, endovascular procedures, open surgical procedures, percutaneous coronary intervention, and coronary artery bypass graft) were higher among symptomatic PAD patients versus control patients. All-cause annualized inpatient admissions (0.46 vs. 0.22 admissions), emergency department/urgent care days (0.27 vs. 0.22 days), and office visit days (12.5 vs. 10.2 days) were higher among symptomatic PAD versus control patients post-index. Annualized all-cause inpatient costs ($8,494 vs. $3,778); outpatient costs ($8,459 vs. $5,692); and total costs ($20,880 vs. $12,501) were higher among symptomatic PAD versus control patients post-index. Only 17.8% of symptomatic PAD patients versus 6.6% of control patients were on clopidogrel pre-index. In the post-index period, clopidogrel prescriptions in the symptomatic PAD population increased to 38.0%. Results were consistent in the regression models with the symptomatic PAD population having a higher number of all-cause post-index inpatient admissions, emergency department/urgent care days, office visit days, inpatient costs, outpatient costs, and total costs versus control patients (P ≤ 0.026).

CONCLUSIONS

Symptomatic PAD patients have significantly higher medical resource use and costs when compared with a matched control population. As the prevalence of symptomatic PAD increases, there will be a significant impact on the population and health care system. The rates of use of evidence-based secondary prevention therapies, such as antiplatelet medication, were low. Therefore, greater effort must be made to increase utilization rates of appropriate treatments to determine if the negative economic and clinical impacts of symptomatic PAD can be minimized.

DISCLOSURES

This study was funded by Merck & Co., Kenilworth, New Jersey. Chase and Heithoff are employees of Merck & Co., Kenilworth, New Jersey, and Upper Gwynedd, Pennsylvania. Friedman and Navaratnam are paid consultants for Merck & Co. Simpson is a paid consultant for Merck, Pfizer, and Amgen and has received speaker's fees from Merck and Pfizer. Study concept and design were contributed by Chase, Navaratnam, and Heilhoff, along with Simpson and Friedman. Friedman collected the data, which was interpreted by Simpson and Navaratnam, along with Friedman. The manuscript was written by Navaratnam and Friedman, along with Chase, Heilhoff and Simpson, and revised by all of the authors.

Novel screening metric for the identification of at-risk peripheral artery disease patients using administrative claims data

Despite high morbidity and mortality associated with peripheral artery disease (PAD), it remains under-diagnosed and under-treated. The objective of this study was to develop a screening metric to identify undiagnosed patients at high risk of developing PAD using administrative data. Commercial claims data from 2010 to 2012 were utilized to develop and internally validate a PAD screening metric. Medicare data were used for external validation. The study population included adults, aged 30 years or older, with new cases of PAD identified using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis/procedure codes or the Healthcare Common Procedure Coding System (HCPCS) codes. Multivariate logistic regression was conducted to determine PAD risk factors used in the development of the screening metric for the identification of at-risk PAD patients. The cumulative incidence of PAD was 6.6%. Sex, age, congestive heart failure, hypertension, chronic renal insufficiency, stroke, diabetes, acute myocardial infarction, transient ischemic attack, hyperlipidemia, and angina were significant risk factors for PAD. A cut-off score of ⩾20 yielded sensitivity, specificity, positive predictive value, negative predictive value, and c-statistics of 83.5%, 60.0%, 12.8%, 98.1%, and 0.78, respectively. By identifying patients at high risk for developing PAD using only administrative data, the use of the current pre-screening metric could reduce the number of diagnostic tests, while still capturing those patients with undiagnosed PAD.

Si vous pensez que c'est juste un mal de jambe… détrompez-vous: ce que les leaders en santé doivent savoir sur la maladie artérielle périphérique

Environ 800 000 Canadiens ont une maladie artérielle périphérique (MAP), une cause majeure d'amputation. Pourtant, le public et les cliniciens connaissent très peu cette maladie. Le présent article traite de la campagne de sensibilisation Si vous pensez que c'est juste un mal de jambe… détrompez-vous que l'Association canadienne du soin des plaies a lancée pour contrer cette tendance. Il porte également sur les facteurs de risque et le dépistage de la MAP, son lien avec le diabète, son traitement et ses soins, ses innovations en matière de soins de la MAP et la nécessité de faire preuve de leadership sur le plan des politiques.

Just leg pain? Think again: What health leaders must know about peripheral arterial disease

Approximately 800,000 Canadians have Peripheral Arterial Disease (PAD). Peripheral arterial disease is also a leading cause of limb amputation. Yet public and clinical awareness of PAD is very limited. This article discusses the "Just Leg Pain? Think Again" awareness campaign the Canadian Association of Wound Care has launched in response. This article also summarizes PAD risk factors, screening, linkage with diabetes, treatment and care interventions, PAD care innovations, and the need for policy leadership on this issue.

Lymphedema prevalence and treatment benefits in cancer: impact of a therapeutic intervention on health outcomes and costs

Background

Lymphedema is a common complication of cancer therapeutics; its prevalence, treatment outcomes, and costs have been poorly defined. The objective of this study was to examine lymphedema prevalence among cancer survivors and to characterize changes in clinical outcomes and costs associated with a defined therapeutic intervention (use of a pneumatic compression devices [PCD]) in a representative, privately insured population.

Methods and Findings

Retrospective analysis of de-identified health claims data from a large national insurer for calendar years 2007 through 2013. Patients were required to have 12 months of continuous insurance coverage prior to PCD receipt (baseline), as well as a 12-month follow-up period. Analyses were performed for individuals with cancer-related lymphedema (n = 1,065). Lymphedema prevalence was calculated: number of patients with a lymphedema claim in a calendar year divided by total number of enrollees. The impact of PCD use was evaluated by comparing rates of a pre-specified set of health outcomes and costs for the 12 months before and after, respectively, PCD receipt. Lymphedema prevalence among cancer survivors increased from 0.95% in 2007 to 1.24% in 2013. PCD use was associated with decreases in rates of hospitalizations (45% to 32%, p<0.0001), outpatient hospital visits (95% to 90%, p<0.0001), cellulitis diagnoses (28% to 22%, p = 0.003), and physical therapy use (50% to 41%, p<0.0001). The average baseline health care costs were high ($53,422) but decreased in the year after PCD acquisition (−$11,833, p<0.0001).

Conclusions

Lymphedema is a prevalent medical condition that is often a defining attribute of cancer survivorship. The problem is associated with high health care costs; Treatment (in this instance, use of PCD) is associated with significant decreases in adverse clinical outcomes and costs.

Outcomes and characteristics of patients undergoing percutaneous angioplasty followed by below-knee or above-knee amputation for peripheral artery disease

OBJECTIVE

Little is known about long-term outcomes among patients who receive percutaneous angioplasty (PTA) for peripheral artery disease (PAD) then undergo below-knee or above-knee amputations. We sought to determine clinical outcomes associated with below-knee or above-knee amputation, along with possible explanatory factors and treatment strategies.

METHODS

Using data from Taiwan's National Health Insurance Research Database from 1997 to 2010, 7,568 adult patients were divided into three groups: lower extremity preserved (LE), below-knee amputation (BK) and above-knee amputation (AK). We assessed outcomes including major adverse cardiovascular events (MACE) and associated risk factors.

RESULTS

Overall MACE was significantly higher in the AK group compared to the LE and BK groups, over a mean follow-up of 2.45 years (hazard ratio [HR]: 1.81; 95% confidence interval [CI]: 1.50-2.18 for AK vs. LE; HR: 1.67; 95% CI: 1.36-2.06 for AK vs. BK). However MACE were similar for the BK and LE groups (HR: 1.08; 95% CI: 0.98-1.20). Overall mortality was highest in the AK group (HR: 1.65, 95% CI: 1.34-2.04 for AK vs. BK). As for patient characteristics, atrial fibrillation was more prevalent in the AK group than in the BK group (17% vs. 7%). Independent risk factors associated with death after above- or below-knee amputation included advanced age, heart failure, dialysis, male gender and high patient volume.

CONCLUSION

The MACE rate was highest in the AK group, whereas the LE and BK groups were similar in this regard. Furthermore, overall mortality increased with larger area of amputation.

The incidence and prevalence of diabetes mellitus and related atherosclerotic complications in Korea: a National Health Insurance Database Study

AIMS/INTRODUCTION

The incidence and prevalence of type 2 diabetes mellitus (T2DM) and related macrovascular complications in Korea were estimated using the Health Insurance Review and Assessment (HIRA) database from 2007-2011, which covers the claim data of 97.0% of the Korean population.

MATERIALS AND METHODS

T2DM, coronary artery disease (CAD), cerebrovascular disease (CVD), and peripheral artery disease (PAD) were defined according to ICD-10 codes. We used the Healthcare Common Procedure Coding System codes provided by HIRA to identify associated procedures or surgeries. When calculating incidence, we excluded cases with preexisting T2DM within two years before the index year. A Poisson distribution was assumed when calculating 95% confidence intervals for prevalence and incidence rates.

RESULTS

The prevalence of T2DM in Korean adults aged 20-89 years was 6.1-6.9% and the annual incidence rates of T2DM ranged from 9.5-9.8/1,000 person-year (PY) during the study period. The incidence rates of T2DM in men and women aged 20-49 years showed decreasing patterns from 2009 to 2011 (P<0.001); by contrast, the incidence in subjects aged 70-79 years showed increased patterns from 2009 to 2011 (P<0.001). The incidence rates of CAD and CVD in patients newly diagnosed with T2DM were 18.84/1,000 PY and 11.32/1,000 PY, respectively, in the year of diagnosis. Among newly diagnosed individuals with T2DM who were undergoing treatment for PAD, 14.6% underwent angioplasty for CAD during the same period.

CONCLUSIONS

Our study measured the national incidences of T2DM, CAD, CVD, and PAD, which are of great concern for public health. We also confirmed the relatively higher risk of CAD and CVD newly detected T2DM patients compared to the general population in Korea.

Study of risk factors associated with peripheral arteriopathy in Japanese-Brazilians from Bauru (SP)

BACKGROUND

Cardiovascular diseases are the major cause of morbidity and mortality in developed and emerging countries. Their main etiology, atherosclerosis, is a disseminated disease that affects the coronary, cerebral and peripheral territories. The peripheral arterial disease (PAD), as well as its consequences, indicates the involvement of the coronary territory. Therefore, its better understanding enables proper treatment, delaying local and long-term complications, reducing the cost to the health system.

OBJECTIVE

This study estimates the percentage of PAD in Japanese-Brazilians from Bauru (SP), recognized by the high prevalence of metabolic disorders such as hypertension (43%), diabetes mellitus (33%) and hypercholesterolemia (60%), and examines the association with risk biomarkers.

METHODS

This cross-sectional population study evaluated 1,330 Japanese-Brazilians of both genders aged≥30 who underwent a complete physical examination, anthropometric measurements, laboratory tests and ankle-brachial index (ABI). Participants with ABI≤0.90 were diagnosed as having PAD. After applying the exclusion criteria, 1,038 individuals were part of the analysis. We used Poisson regression to analyze associations with PAD.

RESULTS

The mean age was 56.8 years and the percentage of PAD was 21.1%, equal among the genders. PAD was associated with smoking (PR 2.16 [1.33 to 3.48]) and hypertension (PR 1.56 [1.12-2.22]).

CONCLUSION

The percentage of PAD in Japanese-Brazilians was similar to other populations of adverse cardiometabolic profile (US PARTNERS and POPADAD). The independent association of PAD with smoking and hypertension, but not with other classical risk factors, may depend on the very high frequencies of metabolic disorders in this population.

Burden of peripheral arterial disease in Europe and the United States: a patient survey

BACKGROUND

The aim of the current study was to quantify the burden of peripheral arterial disease (PAD) with respect to health-related quality of life, work productivity and activity impairment, and healthcare resource utilization.

METHODS

Data were obtained from the 2010 EU National Health and Wellness Survey (NHWS), which included participants from France, Germany, Italy, Spain, and the UK (5 EU, N = 57,805) as well as the 2010 US NHWS (N = 75,000). The NHWS is an annual, cross-sectional, self-administered Internet survey which employs a stratified random sampling frame to match the age and gender characteristics of the NHWS sample with known population statistics. Participants who self-reported a diagnosis of PAD were compared with participants who did not self-report a diagnosis of PAD on health-related quality of life (mental and physical component summary scores and health utilities from the Short Form-12v2), work productivity and activity impairment (Work Productivity and Activity Impairment questionnaire), and healthcare resource use in terms of the number of physician visits, emergency room visits, and hospitalizations in the past six months through regression modeling adjusting for demographics and health characteristics.

RESULTS

A total of 743 (1.29%) and 777 (1.04%) participants self-reported a diagnosis of PAD in the 5 EU and US, respectively. After adjusting for demographics and health characteristics, patients with PAD reported worse health-related quality of life, as measured by health utilities (5 EU: 0.66 vs. 0.70; US: 0.66 vs. 0.72; all p < .05), greater overall work impairment percentage (5 EU: 38.27% vs. 27.48%; US: 23.89% vs. 14.26%) and greater healthcare resource use compared to participants without PAD (all p < .05).

CONCLUSIONS

These results suggest a significant burden for patients with PAD in both the 5 EU countries and the US with respect to both quality of life and economic outcomes. Improved management of these patients may have profound effects from both patient and societal perspectives.

Recent trends in morbidity and in-hospital outcomes of in-patients with peripheral arterial disease: a nationwide population-based analysis

AIMS

The prevalence of peripheral arterial disease (PAD) and especially of critical limb ischaemia (CLI) is announced to rise dramatically worldwide, with a considerable impact on the health care and socio-economic systems. We aimed to characterize the recent trends in morbidity and in-hospital outcome of PAD among all hospitalized patients in the entire German population between 2005 and 2009.

METHODS AND RESULTS

Nationwide data of all hospitalizations in Germany in 2005, 2007, and 2009 were analysed regarding the prevalence of PAD, comorbidities, endovascular (EVR) and surgical revascularizations (SR), major and minor amputations, in-hospital mortality, and associated costs. From 2005 to 2009, total PAD cases increased by 20.7% (from 400 928 to 483 961), with an increase of CLI subset from 40.6 to 43.5%. Total EVR increased by 46%, while thromb-embolectomy, endarterectomy, and patch plastic increased by 67, 42, and 21%, respectively. Peripheral bypasses decreased by 2%. Major amputation decreased from 4.6 to 3.5%, while minor amputation slightly increased from 4.98 to 5.11%. The crude overall in-hospital mortality remained unchanged in claudicants (2.2%), while it decreased from 9.8 to 8.4% in CLI patients. However, mortality rate according to the Poisson model (n/1000 hospital residence days) increased significantly in claudicants (P < 0.001). Total reimbursement costs for PAD in-patient care increased by 21% with an average per case costs in 2009 of €4506 in a claudicant and €6791 in a CLI patient.

CONCLUSION

This population-based analysis documents the significant rise of PAD, particularly of the CLI subset, and highlights the malign prognosis associated with PAD as indicated by high amputation and in-hospital mortality rates.

Practice-based evidence: profiling the safety of cilostazol by text-mining of clinical notes

BACKGROUND

Peripheral arterial disease (PAD) is a growing problem with few available therapies. Cilostazol is the only FDA-approved medication with a class I indication for intermittent claudication, but carries a black box warning due to concerns for increased cardiovascular mortality. To assess the validity of this black box warning, we employed a novel text-analytics pipeline to quantify the adverse events associated with Cilostazol use in a clinical setting, including patients with congestive heart failure (CHF).

METHODS AND RESULTS

We analyzed the electronic medical records of 1.8 million subjects from the Stanford clinical data warehouse spanning 18 years using a novel text-mining/statistical analytics pipeline. We identified 232 PAD patients taking Cilostazol and created a control group of 1,160 PAD patients not taking this drug using 1:5 propensity-score matching. Over a mean follow up of 4.2 years, we observed no association between Cilostazol use and any major adverse cardiovascular event including stroke (OR = 1.13, CI [0.82, 1.55]), myocardial infarction (OR = 1.00, CI [0.71, 1.39]), or death (OR = 0.86, CI [0.63, 1.18]). Cilostazol was not associated with an increase in any arrhythmic complication. We also identified a subset of CHF patients who were prescribed Cilostazol despite its black box warning, and found that it did not increase mortality in this high-risk group of patients.

CONCLUSIONS

This proof of principle study shows the potential of text-analytics to mine clinical data warehouses to uncover 'natural experiments' such as the use of Cilostazol in CHF patients. We envision this method will have broad applications for examining difficult to test clinical hypotheses and to aid in post-marketing drug safety surveillance. Moreover, our observations argue for a prospective study to examine the validity of a drug safety warning that may be unnecessarily limiting the use of an efficacious therapy.

Androgen-deprivation therapy for nonmetastatic prostate cancer is associated with an increased risk of peripheral arterial disease and venous thromboembolism

BACKGROUND

Previous studies demonstrate that androgen-deprivation therapy (ADT) with gonadotropin-releasing hormone (GnRH) agonists and orchiectomy for prostate cancer (PCa) is associated with cardiovascular disease. However, few studies have examined its effect on the peripheral vascular system.

OBJECTIVE

To study the risk of peripheral artery disease (PAD) and venous thromboembolism associated with ADT for PCa.

DESIGN, SETTINGS, AND PARTICIPANTS

This was a population-based observational study of 182 757 US men ≥ 66 yr of age who were diagnosed with nonmetastatic PCa from 1992 to 2007, with a median follow-up of 5.1 yr, of whom 47.8% received GnRH agonists and 2.2% orchiectomy.

MEASUREMENTS

We used Cox proportional hazards models with time-varying treatment variables to adjust for demographic and tumor characteristics in assessing whether treatment with GnRH agonists or orchiectomy were associated with PAD and/or venous thromboembolism.

RESULTS AND LIMITATIONS

GnRH agonist use was associated with an increased risk of incident PAD (adjusted hazard ratio [HR]: 1.16; 95% confidence interval [CI], 1.12-1.21) and incident venous thromboembolism (adjusted HR: 1.10; 95% CI, 1.04-1.15). In addition, orchiectomy was associated with an increased risk of peripheral arterial disease (adjusted HR: 1.13; 95% CI, 1.02-1.26) and venous thromboembolism (adjusted HR: 1.27; 95% CI, 1.11-1.45). Limitations include the observational study design and the inability to assess the use of oral antiandrogens.

CONCLUSIONS

ADT for nonmetastatic PCa is associated with an increased risk of PAD and venous thromboembolism. Additional research is needed to better understand the potential risks and benefits of ADT, so that this treatment can be targeted to patients for whom the benefits are clearest.

An economic evaluation based on a randomized placebo-controlled trial of varenicline in smokers with cardiovascular disease: results for Belgium, Spain, Portugal, and Italy

BACKGROUND

An estimated 17.2% of patients continue to smoke following diagnosis of cardiovascular disease (CVD). To reduce the risk of further morbidity or mortality in cardiovascular patients, smoking cessation has been shown to reduce the risk of mortality by 36% and myocardial infarction by 32%. The objective of this study was to evaluate the long-term health and economic consequences of smoking cessation in patients with CVD.

DESIGN AND METHODS

Results of a randomized clinical trial comparing varenicline plus counselling vs. placebo plus counselling were extrapolated using a Markov model to simulate the lifetime costs and health consequences of smoking cessation in patients with stable CVD. For the base case, we considered a payer's perspective including direct costs attributed to the healthcare provider, measuring cumulative life years (LY) and quality adjusted life (QALY) years as outcome measures. Secondary analyses were conducted from a societal perspective, evaluating lost productivity due to premature mortality. Sensitivity and subgroup analyses were also undertaken. Results were analysed for Belgium, Spain, Portugal, and Italy.

RESULTS

Varenicline plus counselling was associated with a gain in LY and QALY across all countries; relative to placebo plus counselling. From a payer's perspective, incremental cost effectiveness ratios were € 6120 (Belgium), € 5151 (Spain), € 5357 (Portugal), and € 5433 (Italy) per QALY gained. From a societal perspective, varenicline in addition to counselling was less costly than placebo and counselling in all cases. Sensitivity analyses showed little sensitivity in outcomes to model assumptions or uncertainty in model parameters.

CONCLUSIONS

Varenicline in addition to counselling is cost-effective compared to placebo and counselling in smokers with CVD.

Ankle brachial index screening in asymptomatic older adults

BACKGROUND

Screening for peripheral arterial disease (PAD) by measuring ankle brachial index (ABI) in asymptomatic older adults is currently recommended to improve cardiovascular disease risk assessment and establish early treatment, but it is not clear if the strategy is useful in all populations. We examined the prevalence and independent predictors of an abnormal ABI (<0.90), in an asymptomatic sample of 1,017 adults, 60 to 69 years old, enrolled in the ADVANCE study.

METHODS

Baseline data collected between December 2001 and January 2004 among the healthy older controls enrolled in ADVANCE was examined. Frequency distributions and prevalence estimates of an abnormal ABI were calculated, using both standard and modified definitions of ABI. Stepwise logistic regression was used to examine independent predictors of ABI <0.90. Signal detection analysis using recursive partitioning was employed to explore potential demographic and clinical variables related to ABI <0.90.

RESULTS

The prevalence of ABI <0.90 was 2% when using the standard definition and 5% when using a modified definition. ABI prevalence did not differ by gender (P > .05). Compared with subjects who had a normal ABI (0.90-1.39), subjects with an ABI <0.90 were more likely to currently smoke, be physically inactive, have a coronary artery calcium score >10, and an FRS >20% (P ≤ .02). Independent predictors of ABI <0.90 when using the standard definition included currently smoking, physical inactivity, and body mass index >30 (all P values ≤.03), and when using the modified definition included currently smoking, physical inactivity, and hypertension (all P values ≤.04). Currently, smoking was the only significant variable for ABI <0.90 derived through recursive partitioning (P = .02), and indicated that prevalence of ABI <0.90 was 1.5% for nonsmokers, while it was 6.6% for current smokers.

CONCLUSIONS

ABI screening in generally healthy individuals 60 to 69 years old may result in lower prevalence rates of a positive result than estimates based on studies in clinical populations. The modified definition for calculating ABI captured more asymptomatic adults with suspected peripheral arterial disease. More evaluation of the appropriate role of ABI screening in unselected populations is needed before routine screening is implemented.

Atherosclerotic cardiovascular disease screening in adults: American College Of Preventive Medicine position statement on preventive practice

CONTEXT

Atherosclerotic cardiovascular diseases, including coronary heart disease (CHD), carotid artery stenosis (CAS), peripheral artery disease (PAD), and abdominal aortic aneurysm (AAA), affect millions of U.S. adults and are leading causes of morbidity and mortality. There is some uncertainty regarding the utility of certain screening tests for prevention of cardiovascular morbidity and mortality.

EVIDENCE ACQUISITION

Current guidelines and studies pertaining to CHD, CAS, PAD, and AAA screening in the adult population were reviewed.

EVIDENCE SYNTHESIS

CHD risk can be estimated by the Framingham Risk Score (FRS), which is valuable in identifying high-risk asymptomatic adults who may benefit from preventive treatments. There is moderate certainty that the benefits of screening do not outweigh the harms for individuals with asymptomatic CAS. The potential harms associated with routine PAD screening in asymptomatic adults are also likely to exceed benefits. Ultrasonography is a safe, noninvasive, and reliable screening test used to identify AAAs for treatment in men aged >65 years who have ever smoked.

CONCLUSIONS

American College of Preventive Medicine (ACPM) recommends CHD risk assessment using the FRS to guide risk-based therapy. ACPM does not recommend routine screening of the general adult population using electrocardiogram, exercise-stress testing, computed tomography scanning, ankle-brachial index, carotid intima medial thickness, or emerging risk factors, including high-sensitivity C-reactive protein (hs-CRP). ACPM does not recommend routine screening of the general adult population for CAS or PAD. ACPM recommends one-time AAA screening in men aged 65-75 years who have ever smoked. Routine AAA screening in women is not recommended.

Vascular Hospitalization Rates and Costs in Patients With Peripheral Artery Disease in the United States

Background—

Peripheral artery disease (PAD) is common and imposes a high risk of major systemic and limb ischemic events. The RE duction of A therothrombosis for C ontinued H ealth (REACH) Registry is an international prospective registry of patients at risk of atherothrombosis caused by established arterial disease or the presence of ≥3 atherothrombotic risk factors.

Methods and Results—

We compared the 2-year rates of vascular-related hospitalizations and associated costs in US patients with established PAD across patient subgroups. Symptomatic PAD at enrollment was identified on the basis of current intermittent claudication with an ankle-brachial index (ABI) <0.90 or a history of lower-limb revascularization or amputation. Asymptomatic PAD was diagnosed on the basis of an enrollment ABI <0.90 in the absence of symptoms. Overall, 25 763 of the total 68 236–patient REACH cohort were enrolled from US sites; 2396 (9.3%) had symptomatic and 213 (0.8%) had asymptomatic PAD at baseline. One- and cumulative 2-year follow-up data were available for 2137 (82%) and 1677 (64%) of US REACH patients with either symptomatic or asymptomatic PAD, respectively. At 2 years, mean cumulative hospitalization costs, per patient, were $7445, $7000, $10 430, and $11 693 for patients with asymptomatic PAD, a history of claudication, lower-limb amputation, and revascularization, respectively ( P =0.007). A history of peripheral intervention (lower-limb revascularization or amputation) was associated with higher rates of subsequent procedures at both 1 and 2 years.

Conclusions—

The economic burden of PAD is high. Recurring hospitalizations and repeat revascularization procedures suggest that neither patients, physicians, nor healthcare systems should assume that a first admission for a lower-extremity PAD procedure serves as a permanent resolution of this costly and debilitating condition.

Evaluation of the consequences associated with diffuse vascular disease history in patients diagnosed with peripheral arterial disease: estimates from Saskatchewan health data

Background

Peripheral arterial disease (PAD) is caused by narrowing of the arteries in the lower extremities. Limited data exist concerning the impact of diffuse vascular disease (DVD) on prognosis and costs. Thus, the objective of this study is to estimate the impact of DVD on morbidity, mortality and costs.

Methods

PAD was identified between 1985 and 1995 and classified by extent of DVD at diagnosis: none (PAD only, reference group), prior myocardial infarction (MI), prior stroke, prior MI and stroke (MI + stroke), prior transient ischemic attack (TIA). Deaths and hospitalizations were identified through December 2000. Hospitalization costs were estimated from the Ontario Case Cost Project, reported in 2002 $CAD. Proportional hazards analyses measured the impact of vascular involvement on mortality while controlling for risk factors (e.g., age, cardiovascular history).

Results

Overall, 16,439 patients with PAD were included; 14.8% had a prior MI, 10.2% a prior stroke, 2.6% prior MI + stroke, 6.4% prior TIA, two-thirds had PAD only. Median survival was shorter for patients with prior MI (9.3 yrs), TIA (6.3), stroke (4.7), and MI+stroke (4.1) versus the reference group (9.9, p < 0.05, all comparisons). Analyses revealed that the death risk was 60% higher in patients with prior stroke and 84% higher for MI + stroke. Atherothrombotic and bleeding event-related costs were $712, $337, $268, and $170 higher per patient/year of follow-up in patients with a history of MI+stroke, MI, stroke, and TIA, respectively.

Conclusion

Patients diagnosed with PAD with DVD have higher risk of poor outcomes and increased costs.

Medical and cost burden of atherosclerosis among patients treated in routine clinical practice

OBJECTIVE

This investigation estimated medical costs attributable to treatment of patients diagnosed with atherosclerosis in routine US clinical practice.

METHODS

Using Medstat MarketScan claims data, direct costs of care and rates of cardiovascular (CV) events (i.e., myocardial infarction, stroke, revascularization) were examined for patients≥18 years of age with and without a diagnostic code for atherosclerosis from 1/1/2002 through 12/31/2004. Patients with an atherosclerosis ICD-9 code who had no history of CV events in the preceding 12 months (n=75,469) were evaluated. A comparison cohort (n=238,702) was matched on age, gender, geographic region, enrollment time period, and Charlson comorbidity index to estimate incremental costs attributable to atherosclerosis. Differences between patient groups were tested for CV event rates per 1,000 patients and monthly costs for 6 and 12 months before and after diagnosis.

RESULTS

Patients had a mean age of 58 years, 52% men, and a comorbidity index of 0.49. Patients diagnosed with atherosclerosis had significantly higher (p<0.001) rates of CV events (240/1000) after diagnosis, compared with patients without atherosclerosis (32/1000). Mean direct cost of care for patients diagnosed with atherosclerosis was $579/month for 12 months before and $1,074/month for 12 months after diagnosis, an 85% increase. Change in mean annual costs pre/post-index date was $5,232 ($436/month) higher among patients with than those without atherosclerosis (p<0.001).

LIMITATIONS

The study population was restricted to patients with diagnosed clinical atherosclerosis based on specific ICD-9 codes. Matching of the patient cohorts was based on observed characteristics and other unobserved differences may exist.

CONCLUSIONS

Patients with diagnosed atherosclerosis incur significant clinical and economic burden, indicating a need for earlier diagnosis and treatment of atherosclerosis to help in reducing this burden.

Inaccuracy of the administrative database: comparative analysis of two databases for the diagnosis and treatment of intracranial aneurysms

OBJECTIVE

Administrative databases of hospital admissions are increasingly being used, mostly without validation, for epidemiological and clinical outcomes studies. Although it has been difficult to assess the true accuracy of administrative databases, we have identified an opportunity to directly compare the State of Maryland administrative database against a prospectively maintained departmental database at The Johns Hopkins Hospital.

METHODS

Data for patients with the diagnosis of an intracranial aneurysm treated at The Johns Hopkins Hospital over a 17-year period were compared in the State of Maryland administrative database and the neurosurgery departmental database. Discrepancies were clarified by review of the original medical records. The sensitivity, specificity, and positive predictive value of each database were calculated.

RESULTS

The administrative database missed 16% of all cases and was significantly inaccurate in 10 of 12 categories. It had particularly low values in the specificity regarding surgical treatment (67%), the sensitivity regarding endovascular treatment (48%), and the positive predictive value regarding endovascular treatment (30%). By contrast, the lowest score of the departmental database in any category was 97%.

CONCLUSION

We show that this representative administrative database is significantly flawed. Given the exponentially increasing number of research studies based on administrative databases, the pitfalls of research based solely on these need to be recognized. Strong criteria requiring accurate data validation are critical to justify the conclusions of these studies, regardless of their large numbers and complex statistics.

Cost of atrial fibrillation in United States managed care organizations

INTRODUCTION

Atrial fibrillation (AF) has been shown to be associated with high healthcare costs; however, limited data are available from large-scale studies quantifying the overall cost burden of AF in the USA. We therefore aimed to provide an up to date estimate of the overall per-patient costs of AF in managed care organizations across the USA.

METHODS

This retrospective cohort study used claims data from the Integrated Healthcare Information Systems National Managed Care Benchmark Database from January 2005 to December 2006. Patients included in the analysis were aged > or =20 years and had at least two outpatient AF-related claims without hospitalization, or a hospitalization with a primary or secondary discharge diagnosis of AF in 2005. AF-related inpatient and outpatient costs over 12 months from the initial outpatient claim or first hospitalization were examined. For secondary AF hospitalizations, incremental costs associated with AF were measured by comparing costs for patients with AF with a group of matched controls hospitalized without AF.

RESULTS

In total, 35,255 patients diagnosed as having AF (5008 with a primary AF diagnosis, 10,776 with a secondary AF diagnosis, 19,471 with outpatient-managed AF), and 20,571 controls without AF, were included in the analysis. Over 12 months, for primary AF hospitalization patients, inpatient costs were $11,306.53 and outpatient costs were $2826.78 (total $14,133.30) per patient. For hospitalized patients with secondary AF, incremental AF-related inpatient costs were $5181.19 and outpatient costs were $1376.33 (total $6557.52). For AF patients with outpatient management in 2005, 12-month AF-related costs were $2177.30 ($175.47 for AF hospitalizations in 2006 and $2001.85 for outpatient costs).

CONCLUSIONS

Overall costs of AF in the US managed care organizations are high. Costs are primarily due to inpatient expenses. Improved disease management strategies to reduce AF-related hospitalizations and decrease the overall cost burden of AF are needed.

Pharmacologic therapy for intermittent claudication

Peripheral artery disease, defined as atherosclerosis in the lower extremities, affects nearly 8.5 million people in the United States. Due to the frequent asymptomatic manifestation of peripheral artery disease, diagnosis may be delayed and its true incidence underestimated. However, some patients may experience aching pain, numbness, weakness, or fatigue, a condition termed intermittent claudication. Peripheral atherosclerosis is associated with cardiovascular risk and physical impairment; therefore, treatment goals are aimed at decreasing cardiovascular risk, as well as improving quality of life. Little debate exists regarding the management of cardiovascular risk reduction, which consists of both antiplatelet therapy and risk factor modification. Despite recently published guidelines, the treatment of intermittent claudication is less well established and the management remains controversial and uncertain. Exercise remains the first-line therapy for intermittent claudication; however, pharmacologic treatment is often necessary. Although only two prescription drugs have been approved by the U.S. Food and Drug Administration for the treatment of intermittent claudication, several supplements and investigational agents have been evaluated. Therapeutic optimization should balance the anticipated improvements in quality of life with the potential safety risks.

National health care costs of peripheral arterial disease in the Medicare population

Lower extremity peripheral arterial disease (PAD) is prevalent in the Medicare population and is associated with high rates of myocardial infarction, stroke, amputation, and death. Nevertheless, national health expenditures for PAD are not known. We hypothesized that PAD-related costs are high, increase with age, and that treatment rates would be less than known PAD prevalence. The objective was to determine national health care expenditures for PAD in the United States. PAD-related treatment costs were calculated in the elderly, non-disabled Medicare population. The cost analysis relied on the 5% control population for the linked SEER-Medicare data and Medicare claims for the calendar year 2001, identifying PAD cases based on diagnosis and procedure codes. Costs were aggregated separately for inpatient and outpatient treatment and estimates adjusted to reflect the Medicare population. A total of $4.37 billion was spent on PAD-related treatment and 88% of expenditures were for inpatient care. Medicare program outlays totaled $3.87 billion, while enrollees (or their supplemental insurance) spent the remaining $500 million. In total, 6.8% of the elderly Medicare population received treatment for PAD. Treatment increased with age at rates of 4.5%, 7.5%, and 11.8% for individuals aged 65-74, 75-84, and >85 years, respectively. PAD-related costs accounted for approximately 13% of all Medicare Part A and B expenditures for the PAD-treated cohort, and 2.3% of total Medicare Part A and B expenditures. In conclusion, US national PAD-related costs are high, associated with inpatient care, and increase with age. PAD is treated at rates lower than the known PAD prevalence as only approximately one-third of the population with known PAD had detectable PAD-related health care costs in our analysis. The potential impact of earlier PAD detection and use of outpatient preventive strategies on total national PAD health care costs is unknown.