Cost-effectiveness analysis of ankle-brachial index screening in patients with coronary artery disease to optimize medical management.

INTRODUCTION: Screening for peripheral artery disease (PAD) with the ankle-brachial index (ABI) test is currently not recommended in the general population; however, previous studies advocate screening in high-risk populations. Although providers may be hesitant to prescribe low-dose rivaroxaban to patients with coronary artery disease (CAD) alone, given the reduction in cardiovascular events and death associated with rivaroxaban, screening for PAD with the ABI test and accordingly prescribing rivaroxaban may provide additional benefits. We sought to describe the cost-effectiveness of screening for PAD in patients with CAD to optimize this high-risk populations' medical management. METHODS: We used a Markov model to evaluate the ABI test in patients with CAD. We assumed that all patients screened would be candidates for low-dose rivaroxaban. We assessed the cost of ABI screening at $100 per patient and added additional charges for physician visits ($100) and rivaroxaban cost ($470 per month). We used a 30-day cycle and performed analysis over 35 years. We evaluated quality-adjusted life years (QALYs) from previous studies and determined the incremental cost-effectiveness ratio (ICER) according to our model. We performed a deterministic and probabilistic sensitivity analyses of variables with uncertainty and reported them in a Tornado diagram showing the variables with the greatest effect on the ICER. RESULTS: Our model estimates decision costs to screen or not screen at $94,953 and $82,553, respectively. The QALYs gained from screening was 0.060, generating an ICER of $207,491 per QALY. Factors most influential on the ICER were the reduction in all-cause mortality associated with rivaroxaban and the prohibitively high cost of rivaroxaban. If rivaroxaban cost less than $95 per month, this would make screening cost-effective based on a willingness to pay threshold of $50,000 per QALY. CONCLUSIONS: According to our model, screening patients with CAD for PAD to start low-dose rivaroxaban is not currently cost-effective due to insufficient reduction in all-cause mortality and high medication costs. Nevertheless, vascular surgeons have a unique opportunity to prescribe or advocate for low-dose rivaroxaban in patients with PAD to improve cardiovascular outcomes.

Asymptomatic peripheral artery disease: Silent but deadly.

Peripheral Artery Disease (PAD) is a manifestation of atherosclerosis characterized by diminished perfusion of the limb and a state of dysmetabolism. The asymptomatic PAD phenotype is a relatively recent classification. It is unknown how many people currently live with asymptomatic PAD because there are no universal screening recommendations for patients at risk for PAD. Patients with asymptomatic PAD suffer from a similar risk profile of morbidity and mortality as their counterparts with claudication. Despite this increased risk, there is a dearth of clinical investigations into therapies that specifically benefit the asymptomatic PAD population. At present, current pharmacotherapies that have been studied in PAD patient populations do not stratify by symptom status. We believe that further investigation of the impact of existing therapies in this unique population presents an opportunity to reduce morbidity and mortality due to PAD. This can only be achieved in combination with wide-spread adoption of screening for asymptomatic PAD.

Cost-effectiveness analysis of asymptomatic peripheral artery disease screening with the ABI test.

Screening for asymptomatic peripheral artery disease (aPAD) with the ankle-brachial index (ABI) test is hypothesized to reduce disease progression and cardiovascular (CV) events by identifying individuals who may benefit from early initiation of medical therapy. Using a Markov model, we evaluated the cost effectiveness of initiating medical therapy (e.g. statin and ACE-inhibitor) after a positive ankle-brachial index (ABI) screen in 65-year-old patients. We modeled progression to symptomatic PAD (sPAD) and CV events with and without ABI screening, evaluating differences in costs and quality-adjusted life years (QALYs). The cost of the ABI test, physician visit, new medication, CV events, and interventions for sPAD were incorporated in the model. We performed sensitivity analysis on model variables with uncertainty. Our model found an incremental cost of US $338 and an incremental QALY of 0.00380 with one-time ABI screening, resulting in an incremental cost-effectiveness ratio (ICER) of $88,758/QALY over a 35-year period. The variables with the largest effects in the ICER were aPAD disease prevalence, cost of monthly medication after a positive screen and 2-year medication adherence rates. Screening high-risk populations, such as tobacco users, where the prevalence of PAD may be 2.5 times higher, decreases the ICER to $24,092/QALY. Our analysis indicates the cost effectiveness of one-time screening for aPAD depends on prevalence, medication costs, and adherence to therapies for CV disease risk reduction. Screening in higher-risk populations under favorable assumptions about medication adherence results in the most favorable cost effectiveness, but limitations in the primary data preclude definitive assessment of cost effectiveness.

The accuracy and cost-effectiveness of strategies used to identify peripheral artery disease among patients with diabetic foot ulcers.

BACKGROUND: Patients with diabetic foot ulcers (DFUs) should be evaluated for peripheral artery disease (PAD). We sought to estimate the overall diagnostic accuracy for various strategies that are used to identify PAD in this population. METHODS: A Markov model with probabilistic and deterministic sensitivity analyses was used to simulate the clinical events in a population of 10,000 patients with diabetes. One of 14 different diagnostic strategies was applied to those who developed DFUs. Baseline data on diagnostic accuracy of individual noninvasive tests were based on a meta-analysis of previously reported studies. The overall sensitivity and cost-effectiveness of the 14 strategies were then compared. RESULTS: The overall sensitivity of various combinations of diagnostic testing strategies ranged from 32.6% to 92.6%. Cost-effective strategies included ankle-brachial indices for all patients; skin perfusion pressures (SPPs) or toe-brachial indices (TBIs) for all patients; and SPPs or TBIs to corroborate normal pulse examination findings, a strategy that lowered leg amputation rates by 36%. Strategies that used noninvasive vascular testing to investigate only abnormal pulse examination results had low overall diagnostic sensitivity and were weakly dominated in cost-effectiveness evaluations. Population prevalence of PAD did not alter strategy ordering by diagnostic accuracy or cost-effectiveness. CONCLUSIONS: TBIs or SPPs used uniformly or to corroborate a normal pulse examination finding are among the most sensitive and cost-effective strategies to improve the identification of PAD among patients presenting with DFUs. These strategies may significantly reduce leg amputation rates with only modest increases in cost.

Comparing the cost-effectiveness of four novel risk markers for screening asymptomatic individuals to prevent cardiovascular disease (CVD) in the US population.

BACKGROUND: High sensitivity CRP (hsCRP), coronary artery calcification on CT (CT calcium), carotid artery intima media thickness on ultrasound (cIMT) and ankle-brachial index (ABI) improve prediction of cardiovascular disease (CVD) risk, but the benefit of screening with these novel risk markers in the U.S. population is unclear. METHODS AND RESULTS: A microsimulation model evaluating lifelong cost-effectiveness for individuals aged 40-85 at intermediate risk of CVD, using 2003-2004 NHANES-III (N=3736), Framingham Heart Study, U.S. Vital Statistics, meta-analyses of independent predictive effects of the four novel risk markers and treatment effects was constructed. Using both an intention-to-treat (assumes adherence <100% and incorporates disutility from taking daily medications) and an as-treated (100% adherence and no disutility) analysis, quality adjusted life years (QALYs), lifetime costs (2014 US $), and incremental cost-effectiveness ratios (ICER in $/QALY gained) of screening with hsCRP, CT coronary calcium, cIMT and ABI were established compared with current practice, full adherence to current guidelines, and ubiquitous statin therapy. In the intention-to-treat analysis in men, screening with CT calcium was cost effective ($32,900/QALY) compared with current practice. In women, screening with hsCRP was cost effective ($32,467/QALY). In the as-treated analysis, statin therapy was both more effective and less costly than all other strategies for both men and women. CONCLUSIONS: When a substantial disutility from taking daily medication is assumed, screening men with CT coronary calcium is likely to be cost-effective whereas screening with hsCRP has value in women. The individual perceived disutility for taking daily medication should play a key role in the decision.

Screen or not to screen for peripheral arterial disease: guidance from a decision model.

BACKGROUND: Asymptomatic Peripheral Arterial Disease (PAD) is associated with greater risk of acute cardiovascular events. This study aims to determine the cost-effectiveness of one time only PAD screening using Ankle Brachial Index (ABI) test and subsequent anti platelet preventive treatment (low dose aspirin or clopidogrel) in individuals at high risk for acute cardiovascular events compared to no screening and no treatment using decision analytic modelling. METHODS: A probabilistic Markov model was developed to evaluate the life time cost-effectiveness of the strategy of selective PAD screening and consequent preventive treatment compared to no screening and no preventive treatment. The analysis was conducted from the Dutch societal perspective and to address decision uncertainty, probabilistic sensitivity analysis was performed. Results were based on average values of 1000 Monte Carlo simulations and using discount rates of 1.5% and 4% for effects and costs respectively. One way sensitivity analyses were performed to identify the two most influential model parameters affecting model outputs. Then, a two way sensitivity analysis was conducted for combinations of values tested for these two most influential parameters. RESULTS: For the PAD screening strategy, life years and quality adjusted life years gained were 21.79 and 15.66 respectively at a lifetime cost of 26,548 Euros. Compared to no screening and treatment (20.69 life years, 15.58 Quality Adjusted Life Years, 28,052 Euros), these results indicate that PAD screening and treatment is a dominant strategy. The cost effectiveness acceptability curves show 88% probability of PAD screening being cost effective at the Willingness To Pay (WTP) threshold of 40000 Euros. In a scenario analysis using clopidogrel as an alternative anti-platelet drug, PAD screening strategy remained dominant. CONCLUSION: This decision analysis suggests that targeted ABI screening and consequent secondary prevention of cardiovascular events using low dose aspirin or clopidogrel in the identified patients is a cost-effective strategy. Implementation of targeted PAD screening and subsequent treatment in primary care practices and in public health programs is likely to improve the societal health and to save health care costs by reducing catastrophic cardiovascular events.

[Ankle brachial index: motivations, training, and practices among 165 general practitioners in Île-de-France]. / Index de pression systolique et médecine de ville : motivation, formation, mesure et valorisation de l'acte. Enquête auprès d'un échantillon de 165 médecins généralistes d'Île-de-France.

UNLABELLED: Peripheral arterial disease (PAD) is under-diagnosed despite its predictive value for cardiovascular mortality. The ankle brachial index (ABI), a simple reliable measure recommended by the French health authorities to detect and evaluate the severity of PAD, is used by too few general practitioners (GPs). OBJECTIVE: This study aimed at identifying motivations and barriers for using ABI in general practice. METHOD: A representative, descriptive, cross-sectional survey was conducted amongst 165 GPs practicing in Île-de-France who were interviewed using stratified quotas. RESULTS: Although 1 out of 5 GPs considered ABI to be an irrelevant indicator, most had a favorable opinion about its use (OR: 4.9 [CI 95 %: 4.2-5.7]). Only 42 % (CI 95 %: 34 %-49 %) of GPs knew ABI was recommended by the health authorities. This information had a critical impact on the acceptance of ABI relevancy (OR: 3.7 [CI 95 %: 3.2-4.2]). Training reinforced acceptance (OR: 5.0 [CI 95 %: 4.4-5.6]) and pre-residency education provided a better understanding of ABI (OR: 2.8 [CI 95 %: 2.3-3.4]). Time needed to measure ABI was the main barrier (OR: 0.6 [CI 95 %: 0.6-0.7]). A Doppler-calculation kit (OR: 11.8 [CI 95 %: 8.9-15.6]), equipment cost≤300Euros (OR: 3.4 [CI 99 %: 3.0-3.9]), a specific fee in addition to the regular consultation fee (OR: 2.6 [CI 95 %: 2.3-3.0]) and inclusion of ABI in the GP's evaluation scheme (OR: 2.6 [CI 95 %: 2.3-2.9]) would motivate more GPs. Seven out of 10 GPs agreed that ABI has a positive impact on patient adherence to treatment and follow-up, but ABI remained underexploited for symptomatic patients (OR: 0.4 [CI 95 %: 0.3-0.4]). CONCLUSION: Better communication and training together with an upgraded status for ABI would provide motivation for GPs to measure ABI.

Relation of socioeconomic position with ankle-brachial index.

Potential upstream determinants of coronary heart disease (CHD) include life-course socioeconomic position (e.g., childhood socioeconomic circumstances, own education and occupation); however, several plausible biological mechanisms by which socioeconomic position (SEP) may influence CHD are poorly understood. Several CHD risk factors appear to be more strongly associated with SEP in women than in men; little is known as to whether any CHD risk factors may be more strongly associated with SEP in men. Objectives were to evaluate whether cumulative life-course SEP is associated with a measurement of subclinical atherosclerosis, the ankle-brachial index (ABI), in men and women. This study was a prospective analysis of 1,454 participants from the Framingham Heart Study Offspring Cohort (mean age 57 years, 53.8% women). Cumulative SEP was calculated by summing tertile scores for father's education, own education, and own occupation. ABI was dichotomized as low (≤1.1) and normal (>1.1 to 1.4). After adjustment for age and CHD risk factors cumulative life-course SEP was associated with low ABI in men (odds ratio [OR] 2.04, 95% confidence interval [CI] 1.22 to 3.42, for low vs high cumulative SEP score) but not in women (OR 0.86, 95% CI 0.56 to 1.33). Associations with low ABI in men were substantially driven by their own education (OR 4.13, 95% CI 1.86 to 9.16, for lower vs higher than high school education). In conclusion, cumulative life-course SEP was associated with low ABI in men but not in women.