Cost-effectiveness of endarterectomy in patients with asymptomatic carotid artery stenosis

Do Integrated Systems of Stroke Care Improve Symptom to Surgery Times in Patients with Symptomatic Carotid Stenosis? A Single Centre Decision Tree Analysis

OBJECTIVE

The objective of this study was to examine the impact of an integrated system of stroke care on symptom to surgery times, cost-effectiveness, and quality of life measures in patients with symptomatic carotid stenosis.

METHODS

Patients who underwent carotid endarterectomy (CEA) in a regional vascular centre between April 1, 2011, and March 31, 2016, were identified from the National Vascular Registry (NVR). Risk of stroke on medical therapy for each patient was calculated using the Oxford stroke risk calculator. Symptom to surgery times were compared among patients referred from a stroke service providing an integrated stroke care and the stroke service in an adjacent NHS trust which provides standard urgent referral pathway. A decision analytic Markov process model was constructed to determine the cost-effectiveness of CEA versus medical treatment in patients who followed the standard and integrated pathways. This model examined the lifetime costs and health benefits of CEA through each pathway.

RESULTS

A total of 376 patients underwent CEA, of whom 243 were managed through the integrated stroke pathway and 133 through the standard urgent referral pathway. Median symptom to surgery time was 11 (0-66) days for the former and 15 (3-90) days for the latter (p < .001). There was no significant difference in peri-operative stroke death rate between integrated (2.1%) and standard (1.5%) pathways (chi-square = 0.14, p = .73). CEA through the integrated pathway improved quality adjusted life expectancy by an additional 0.13 (0.64 QALYs [integrated pathway] to 0.51 QALYs [standard pathway]) and was associated with an incremental lifetime cost benefit of £2203.4.

CONCLUSIONS

An integrated stroke system of care is cost-effective and associated with significant improvements in quality adjusted life years.

M1- and M2-Type Macrophage Responses Are Predictive of Adverse Outcomes in Human Atherosclerosis

Atherosclerosis is an inflammatory disease caused by endothelial injury, lipid deposition, and oxidative stress. This progressive disease can be converted into an acute clinical event by plaque rupture and thrombosis. In the context of atherosclerosis, the underlying cause of myocardial infarction and stroke, macrophages uniquely possess a dual functionality, regulating lipid accumulation and metabolism and sustaining the chronic inflammatory response, two of the most well-documented pathways associated with the pathogenesis of the disease. Macrophages are heterogeneous cell populations and it is hypothesized that, during the pathogenesis of atherosclerosis, macrophages in the developing plaque can switch from a pro-inflammatory (MΦ1) to an anti-inflammatory (MΦ2) phenotype and vice versa, depending on the microenvironment. The aim of this study was to identify changes in macrophage subpopulations in the progression of human atherosclerotic disease. Established atherosclerotic plaques from symptomatic and asymptomatic patients with existing coronary artery disease undergoing carotid endarterectomy were recruited to the study. Comprehensive histological and immunohistochemical analyses were performed to quantify the cellular content and macrophage subsets of atherosclerotic lesion. In parallel, expression of MΦ1 and MΦ2 macrophage markers were analyzed by real-time PCR and Western blot analysis. Gross analysis and histological staining demonstrated that symptomatic plaques presented greater hemorrhagic activity and the internal carotid was the most diseased segment, based on the predominant prevalence of fibrotic and necrotic tissue, calcifications, and hemorrhagic events. Immunohistochemical analysis showed that both MΦ1 and MΦ2 macrophages are present in human plaques. However, MΦ2 macrophages are localized to more stable locations within the lesion. Importantly, gene and protein expression analysis of MΦ1/MΦ2 markers evidenced that MΦ1 markers and Th1-associated cytokines are highly expressed in symptomatic plaques, whereas expression of the MΦ2 markers, mannose receptor (MR), and CD163 and Th2 cytokines are inversely related with disease progression. These data increase the understanding of atherosclerosis development, identifying the cellular content of lesions during disease progression, and characterizing macrophage subpopulation within human atherosclerotic plaques.

Systematic Review of Guidelines for the Management of Asymptomatic and Symptomatic Carotid Stenosis

BACKGROUND AND PURPOSE

We systematically compared and appraised contemporary guidelines on management of asymptomatic and symptomatic carotid artery stenosis.

METHODS

We systematically searched for guideline recommendations on carotid endarterectomy (CEA) or carotid angioplasty/stenting (CAS) published in any language between January 1, 2008, and January 28, 2015. Only the latest guideline per writing group was selected. Each guideline was analyzed independently by 2 to 6 authors to determine clinical scenarios covered, recommendations given, and scientific evidence used.

RESULTS

Thirty-four eligible guidelines were identified from 23 different regions/countries in 6 languages. Of 28 guidelines with asymptomatic carotid artery stenosis procedural recommendations, 24 (86%) endorsed CEA (recommended it should or may be provided) for ≈50% to 99% average-surgical-risk asymptomatic carotid artery stenosis, 17 (61%) endorsed CAS, 8 (29%) opposed CAS, and 1 (4%) endorsed medical treatment alone. For asymptomatic carotid artery stenosis patients considered high-CEA-risk because of comorbidities, vascular anatomy, or undefined reasons, CAS was endorsed in 13 guidelines (46%). Thirty-one of 33 guidelines (94%) with symptomatic carotid artery stenosis procedural recommendations endorsed CEA for patients with ≈50% to 99% average-CEA-risk symptomatic carotid artery stenosis, 19 (58%) endorsed CAS and 9 (27%) opposed CAS. For high-CEA-risk symptomatic carotid artery stenosis because of comorbidities, vascular anatomy, or undefined reasons, CAS was endorsed in 27 guidelines (82%). Guideline procedural recommendations were based only on results of trials in which patients were randomized 12 to 34 years ago, rarely reflected medical treatment improvements and often understated potential CAS hazards. Qualifying terminology summarizing recommendations or evidence lacked standardization, impeding guideline interpretation, and comparison.

CONCLUSIONS

This systematic review has identified many opportunities to modernize and otherwise improve carotid stenosis management guidelines.

Impact of Real-World Adherence with Best Medical Treatment on Cost-Effectiveness of Carotid Endarterectomy for Asymptomatic Carotid Artery Stenosis

BACKGROUND

To present a model of decision and cost-effectiveness analysis that allows assessing the trade-off between the short-term risks of performing a carotid endarterectomy (CEA) and the rate of preventable future events and the impact of real-world adherence of best medical treatment (BMT) on cost-effectiveness of both therapeutic options.

METHODS

We used data from the current literature to define values for a base case and perform a sensitivity analysis. The primary end point was a comparison of the fatal and disabling stroke-free survival during a 5-year period in a cohort of hypothetical patients who presented asymptomatic severe carotid stenosis and were treated with either prophylactic CEA or adherent and nonadherent best medical treatment, respectively.

RESULTS

The difference in estimated fatal and disabling stroke-free survival favoring endarterectomy in patients with asymptomatic severe carotid stenosis is 44 days over the course of 5 years in case of nonadherent best medical treatment. Over a 5-year time horizon, prophylactic CEA would be cost-effective in 50.8% of bootstrap replicates and nonpersistent BMT might be economically dominant in 11.1%. The probability that CEA would be cost-effective at a willingness-to-pay (WTP) threshold of Euro 50,000/quality-adjusted life year gained was 71.8%. In 17.9% prophylactic CEA would be more costly and effective than persistent BMT, but its incremental cost-effectiveness ratio was greater than the WTP, so persistent BMT would be optimal.

CONCLUSIONS

In this model, in case of real-world drug adherence, it was likely that a strategy of early endarterectomy might be a cost-effective or even the dominant therapeutic option in comparison with a strategy of medical therapy alone (deferred surgery). If background any-territory stroke rates on contemporary medical therapy would fall substantially below 0.7%, surgery would cease to be cost-effective.

The role of cost-effectiveness for vascular surgery service provision in the United Kingdom

OBJECTIVE

The cost of health care is increasingly becoming an international issue, with many health care systems requiring evaluation of cost when agreeing to fund health care. In the United Kingdom (UK), for example, the National Institute for Health and Care Excellence highlights the importance of using cost-effectiveness analyses to facilitate the effective use of resources. This study evaluates the use of cost-effectiveness analyses and the provision of vascular surgery.

METHODS

A systematic review of published literature was performed. UK-based studies assessing cost-effectiveness or cost-utility of superficial venous interventions, abdominal aortic aneurysm (AAA) repair, and carotid endarterectomy (CEA) were included. All included studies were quality assessed to determine the overall strength of UK economic evidence for each intervention.

RESULTS

Four superficial venous, six AAA, and two CEA studies met the inclusion criteria. After quality assessment, the UK evidence supporting the cost-effectiveness of superficial venous intervention was graded strong. The economic evidence for asymptomatic and symptomatic CEA was graded limited and insufficient, respectively, owing to a paucity of UK literature in this field. There was strong UK economic evidence affirming that endovascular aneurysm repair (EVAR) is unlikely to be a cost-effective alternative to open repair.

CONCLUSIONS

There is strong economic evidence for symptomatic superficial venous intervention. However, funding for varicose vein treatments remains controversial. Future economic analyses are required for symptomatic and asymptomatic CEA to better advise national policy. Despite strong economic evidence, current UK guidance is for EVAR over open repair in the elective setting, with the majority of elective AAA repairs being EVAR.

Economic evaluation of using a genetic test to direct breast cancer chemoprevention in white women with a previous breast biopsy

BACKGROUND

Tamoxifen therapy reduces the risk of breast cancer but increases the risk of serious adverse events including endometrial cancer and thromboembolic events.

OBJECTIVES

The cost effectiveness of using a commercially available breast cancer risk assessment test (BREVAGen™) to inform the decision of which women should undergo chemoprevention by tamoxifen was modeled in a simulated population of women who had undergone biopsies but had no diagnosis of cancer.

METHODS

A continuous time, discrete event, mathematical model was used to simulate a population of white women aged 40-69 years, who were at elevated risk for breast cancer because of a history of benign breast biopsy. Women were assessed for clinical risk of breast cancer using the Gail model and for genetic risk using a panel of seven common single nucleotide polymorphisms. We evaluated the cost effectiveness of using genetic risk together with clinical risk, instead of clinical risk alone, to determine eligibility for 5 years of tamoxifen therapy. In addition to breast cancer, the simulation included health states of endometrial cancer, pulmonary embolism, deep-vein thrombosis, stroke, and cataract. Estimates of costs in 2012 US dollars were based on Medicare reimbursement rates reported in the literature and utilities for modeled health states were calculated as an average of utilities reported in the literature. A 50-year time horizon was used to observe lifetime effects including survival benefits.

RESULTS

For those women at intermediate risk of developing breast cancer (1.2-1.66 % 5-year risk), the incremental cost-effectiveness ratio for the combined genetic and clinical risk assessment strategy over the clinical risk assessment-only strategy was US$47,000, US$44,000, and US$65,000 per quality-adjusted life-year gained, for women aged 40-49, 50-59, and 60-69 years, respectively (assuming a price of US$945 for genetic testing). Results were sensitive to assumptions about patient adherence, utility of life while taking tamoxifen, and cost of genetic testing.

CONCLUSIONS

From the US payer's perspective, the combined genetic and clinical risk assessment strategy may be a moderately cost-effective alternative to using clinical risk alone to guide chemoprevention recommendations for women at intermediate risk of developing breast cancer.

Applying the payoff time framework to carotid artery disease management

BACKGROUND

and

OBJECTIVE

Asymptomatic stenosis of the carotid arteries is associated with stroke. Carotid revascularization can reduce the future risk of stroke but can also trigger an immediate stroke. The objective was to model the generic relationship between immediate risk, long-term benefit, and life expectancy for any one-time prophylactic treatment and then apply the model to the use of revascularization in the management of asymptomatic carotid disease.

METHODS

In the "payoff time" framework, the possibility of losing quality-adjusted life-years (QALYs) because of revascularization failure is conceptualized as an "investment" that is eventually recouped over time, on average. Using this framework, we developed simple mathematical forms that define relationships between the following: perioperative probability of stroke (P); annual stroke rate without revascularization (r0); annual stroke rate after revascularization, conditional on not having suffered perioperative stroke (r1); utility levels assigned to the asymptomatic state (ua) and stroke state (us); and mortality rates (λ).

RESULTS

In patients whose life expectancy is below a critical life expectancy (CLE = P/(1-P)r0-r1, the "investment" will never pay off, and revascularization will lead to loss of QALYs, on average. CLE is independent of utilities assigned to the health states if a rank ordering exists in which ua > us. For clinically relevant values (P = 3%, r0 = 1%, r1 = 0.5%), the CLE is approximately 6.4 years, which is longer than published guidelines regarding patient selection for revascularization.

CONCLUSIONS

In managing asymptomatic carotid disease, the payoff time framework specifies a CLE beneath which patients, on average, will not benefit from revascularization. This formula is suitable for clinical use at the patient's bedside and can account for patient variability, the ability of clinicians who perform revascularization, and the particular revascularization technology that is chosen.

Modelling the cost-effectiveness of carotid endarterectomy for asymptomatic stenosis5

Background

The aim of this study was to model the cost-effectiveness of carotid endarterectomy for asymptomatic stenosis versus medical therapy based on 10-year data from the Asymptomatic Carotid Surgery Trial (ACST).

Methods

This was a cost–utility analysis based on clinical effectiveness data from the ACST with UK-specific costs and stroke outcomes. A Markov model was used to calculate the incremental cost-effectiveness ratio (ICER, or cost per additional quality-of-life year) for a strategy of early endarterectomy versus medical therapy for the average patient and published subgroups. An exploratory analysis considered contemporary event rates.

Results

The ICER was £ 7584 per additional quality-adjusted life-year (QALY) for the average patient in the ACST. At thresholds of £ 20 000 and £ 30 000 there was a 74 and 84 per cent chance respectively of early endarterectomy being cost-effective. The ICER for men below 75 years of age was £ 3254, and that for men aged 75 years or above was £ 71 699. For women aged under 75 years endarterectomy was less costly and more effective than medical therapy; for women aged 75 years or more endarterectomy was less effective and more costly than medical therapy. At contemporary perioperative event rates of 2·7 per cent and background any-territory stroke rates of 1·6 per cent, early endarterectomy remained cost-effective.

Conclusion

In the ACST, early endarterectomy was predicted to be cost-effective in those below 75 years of age, using a threshold of £ 20 000 per QALY. If background any-territory stroke rates fell below 1 per cent per annum, early endarterectomy would cease to be cost-effective.

Limited economic evidence of carotid artery stenosis diagnosis and treatment: a systematic review

The objective of this article is to assess the availability and validity of economic evaluations of carotid artery stenosis (CS) diagnosis and treatment.

DESIGN

Systematic review of economic evaluations of the diagnosis and treatment of CS.

METHODS

Systematic review of full economic evaluations published in Medline and Google Scholar up until 28 February 2012. Based on economic checklists (Evers and Philips), the identified studies were classified as high, medium, or low quality.

RESULTS

Twenty-three evaluations were identified. The study quality ranged from 26% to 84% of all achievable points (Evers). Seven studies were of high, eight of medium and eight of low quality. No comparison was made between carotid angioplasty and stenting (CAS) and best medical treatment (BMT). For subjects with severe stenosis, comparisons of carotid endarterectomy (CEA) and BMT were also missing. Three of five studies dealing with pre-operative imaging found that duplex Doppler ultrasound (US) was cost-effective compared with carotid angiogram (AG).

CONCLUSIONS

There is a huge lack of high-quality studies and of studies that confirm published results. Also, for a given study quality, the most cost-effective treatment strategy is still unknown in some cases ('CAS' vs. 'BMT', 'US combined with magnetic resonance angiography supplemented with AG' vs. 'US combined with computer tomography angiography').

Carotid endarterectomy in asymptomatic patients with limited life expectancy

BACKGROUND AND PURPOSE

Data from randomized trials assert that asymptomatic patients undergoing carotid endarterectomy (CEA) must live 3 to 5 years to realize the benefit of surgery. We examined how commonly CEA is performed among asymptomatic patients with limited life expectancy.

METHODS

Within the American College of Surgeons National Quality Improvement Project we identified 8 conditions associated with limited life expectancy based on survival estimates using external sources. We then compared rates of 30-day stroke, death, and myocardial infarction after CEA between asymptomatic patients with and without life-limiting conditions.

RESULTS

Of 12,631 CEAs performed in asymptomatic patients, 2525 (20.0%) were in patients with life-limiting conditions or diagnoses. The most common conditions were severe chronic obstructive pulmonary disease and American Society of Anesthesiologists Class IV designation. Patients with life-limiting conditions had significantly higher rates of perioperative complications, including stroke (1.8% versus 0.9%, P<0.001), death (1.4% versus 0.3%, P<0.001), and stroke/death (2.9% versus 1.1%, P<0.001). Even after adjustment for other comorbidities, patients with life-limiting conditions were nearly 3 times more likely to experience perioperative stroke or death than those without these conditions (OR, 2.8; 95% CI, 2.1-3.8; P<0.001).

CONCLUSION

CEA is performed commonly in asymptomatic patients with life-limiting conditions. Given the high rates of postoperative stroke/death in these patients as well as their limited life expectancy, the net benefit of CEA in this population remains uncertain. Health policy research examining the role of CEA in asymptomatic patients with life-limiting conditions is necessary and may serve as a potential source for significant healthcare savings in the future.

Evidence-based treatment of carotid artery stenosis

Carotid atheromatous disease is an important cause of stroke. Carotid endarterectomy (CEA) is a well-established option for reducing the risk of subsequent stroke due to symptomatic stenosis (> 50%). With adequately low perioperative risk (< 3%) and sufficient life expectancy, CEA may be used for asymptomatic stenosis (> 60%). Recently, carotid angioplasty and stent placement (CAS) has emerged as an alternative revascularization technique. Trial design considerations are discussed in relation to trial results to provide an understanding of why some trials were considered positive whereas others were not. This review then addresses both the original randomized studies showing that CEA is superior to best medical management and the newer studies comparing the procedure to stent insertion in both symptomatic and asymptomatic populations. Additionally, recent population-based studies show that improvements in best medical management may be lowering the stroke risk for asymptomatic stenosis. Finally, the choice of revascularization technique is discussed with respect to symptom status. Based on current evidence, CAS should remain limited to specific indications.

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.

Asymptomatic carotid artery stenosis--medical therapy alone versus medical therapy plus carotid endarterectomy or stenting

Vascular surgery has matured to the point that there exists robust bodies of literature exploring many of our therapies. However, this evidence is but one of the factors that dictate medical practice. Others include local patient demographics, the practical implications of healthcare delivery, and an individual surgeon's interpretation of this evidence, which can be somewhat subjective. As a result, there are numerous examples of vascular specialists' practice patterns differing depending on their geographic location. Recognizing this, the Editors of the Journal of Vascular Surgery and the European Journal of Vascular and Endovascular Surgery have developed a series of Trans-Atlantic Debates to explore these instances. The inaugural debate explores the controversial question of how best to manage asymptomatic carotid artery stenoses. Our debators, Peter Schneider and Ross Naylor, offer reasoned and passionate arguments to defend their differing approaches. We trust that this addition to our journals will prove enlightening and, perhaps, entertaining.

Cost-effectiveness analysis of protected carotid artery stent placement versus endarterectomy in high-risk patients

PURPOSE

To determine the cost-effectiveness of carotid angioplasty with stent placement (CAS) under emboli protection versus carotid endarterectomy (CEA) in patients with severe carotid stenosis considered to be at high surgical risk for CEA.

METHODS

The probabilities of various outcomes were adopted from the SAPPHIRE trial results. The quality-adjusted life year (QALYs) associated with each treatment modality were estimated by using the frequencies of various quality-adjusted outcomes (QALY weights of ipsilateral stroke, myocardial infarction, and death). Total cost associated with each intervention was computed using the frequency of stroke, myocardial infarction, and death in each group. Costs are expressed in 2006 US$. Incremental cost-effectiveness ratios (ICERs) were estimated for a 1-year postprocedure period.

RESULTS

The mean (range) estimated net costs at 1 year for patients treated with CAS and CEA were $12,782 ($12,205-$13,563) and $8,916 ($8,267-$9,766), respectively. Overall QALYs for the CAS and CEA groups were 0.753 and 0.701 [within a range of 0.0 (meaning death) to 0.815 (meaning no adverse events)]. The mean cost per QALY gained for CAS was $16,223 ($15,315-$17,474) and the mean cost per QALY gained for CEA was $12,745 ($11,372-$14,605). The estimated median ICER for CAS versus CEA treatment was $67,891 (-$129,372 to $379,661).

CONCLUSION

The proven non-inferiority of CAS versus CEA in high-surgical-risk patients with severe carotid stenosis might provide a marginal benefit that is offset by the higher cost associated with this procedure.

Cost-effectiveness analysis of general anaesthesia versus local anaesthesia for carotid surgery (GALA Trial)

Background

Health outcomes and costs are both important when deciding whether general (GA) or local (LA) anaesthesia should be used during carotid endarterectomy. The aim of this study was to assess the cost-effectiveness of carotid endarterectomy under LA or GA in patients with symptomatic or asymptomatic carotid stenosis for whom surgery was advised.

Methods

Using patient-level data from a large, multinational, randomized controlled trial (GALA Trial) time free from stroke, myocardial infarction or death, and costs incurred were evaluated. The cost-effectiveness outcome was incremental cost per day free from an event, within a time horizon of 30 days.

Results

A patient undergoing carotid endarterectomy under LA incurred fewer costs (mean difference £178) and had a slightly longer event-free survival (difference 0·16 days, but the 95 per cent confidence limits around this estimate were wide) compared with a patient who had GA. Existing uncertainty did not have a significant impact on the decision to adopt LA, over a wide range of willingness-to-pay values.

Conclusion

If cost-effectiveness was considered in the decision to adopt GA or LA for carotid endarterectomy, given the evidence provided by this study, LA is likely to be the favoured treatment for patients for whom either anaesthetic approach is clinically appropriate.

Genetics of ischemic stroke: inheritance of a sporadic disorder

Stroke is a common neurologic disorder associated with comorbidities such as obesity, hypertension, hypercholesterolemia, and diabetes mellitus. Smoking or being the first-degree relative of a stroke patient can independently almost double the risk of ischemic stroke, supporting the hypothesis that stroke results from an intricate interplay between genes and the environment. Several candidate genes have been nominated but not confirmed as influencing stroke susceptibility and phenotype. A number of genes involved in monogenic forms of disease have been identified as causative in familial stroke. Herein we discuss these genes and the potential role of genetics in the more common sporadic form of stroke and therapeutic intervention strategies.