Cost-effectiveness of pharmacologic and invasive therapies for stroke prophylaxis in atrial fibrillation

The Cost Effectiveness of LAA Exclusion

Left atrial appendage (LAA) exclusion strategies are increasingly utilized for stroke prevention in lieu of oral anticoagulants. Reductions in bleeding risk and long-term compliance issues bundled with comparable stroke prevention benefits have made these interventions increasingly attractive. Unfortunately, healthcare funding remains limited. Comparative cost economic analyses are therefore critical in optimizing resource allocation. In this review we seek to discourse the cost economics analysis of LAA exclusion over available therapeutic alternatives (warfarin and the new oral anticoagulants (NOACs)). .

Economic Burden of Undiagnosed Nonvalvular Atrial Fibrillation in the United States

Atrial fibrillation (AF) may be clinically silent and therefore undiagnosed. To date, no estimates of the direct medical cost of undiagnosed AF exist. We estimated the United States (US) incremental cost burden of undiagnosed nonvalvular AF nationally using administrative claims data. To calculate the incremental costs of undiagnosed AF, we compared annual medical costs (in 2014 US Dollars) for patients with AF compared to propensity-matched controls and multiplied this by estimates of undiagnosed AF prevalence derived from the same data sources. The study population included US residents aged ≥18 years with 24 months of continuous enrollment drawn from 2 large administrative claims databases. Mean per capita medical spending for patients with AF aged from 18 to 64 year was $38,861 (95% confidence interval [CI] $35,781 to $41,950) compared to $28,506 (95% CI $28,409 to $28,603) for similar patients without AF (incremental cost difference $10,355, p <0.001); total spending for patients aged ≥65 years with AF was $25,322 (95% CI $25,049 to $25,595) compared to $21,706 (95% CI $21,563 to $21,849) for similar patients without AF (incremental cost difference $3,616, p <0.001). Using estimates of the US prevalence of undiagnosed AF (596,000) drawn from the same data, we estimated that the US incremental cost burden of undiagnosed nonvalvular AF is $3.1 billion (95% CI $2.7 to $3.7 billion). In conclusion, the direct medical costs for patients with undiagnosed AF are greater than patients with similar observable characteristics without AF and strategies to identify and treat patients with undiagnosed AF could lead to sizable reductions in stroke sequelae and associated costs.

Evaluating the Cost-effectiveness of Catheter Ablation of Atrial Fibrillation

Atrial fibrillation (AF) is one of the most common cardiac conditions treated in primary care and specialty cardiology settings, and is associated with considerable morbidity, mortality and cost. Catheter ablation, typically by electrically isolating the pulmonary veins and surrounding tissue, is more effective at maintaining sinus rhythm than conventional antiarrhythmic drug therapy and is now recommended as first-line therapy. From a value standpoint, the cost-effectiveness of ablation must incorporate the upfront procedural costs and risks with the benefits of longer term improvements in quality of life (QOL) and healthcare utilisation. Here, we present a primer on cost-effectiveness analysis (CEA), review the data on cost-effectiveness of AF ablation and outline key areas for further investigation.

Comparison of Medical Costs of Patients With Atrial Fibrillation Unsuitable for Warfarin Treatment With Apixaban or Aspirin Based on AVERROES Trial

Background:

The AVERROES trial name is the following: The Apixaban Versus Acetylsalicylic Acid (ASA) to Prevent Stroke in Atrial Fibrillation Patients Who Have Failed or Are Unsuitable for Vitamin K Antagonist Treatment (AVERROES) trial demonstrated that apixaban reduced the risk of stroke relative to aspirin, without significantly increasing major bleeding risk in patients with atrial fibrillation (AF) considered unsuitable for warfarin therapy. Based on AVERROES trial results, this study compared the medical costs for clinical end points among patients with AF treated with either apixaban or aspirin.

Methods:

Medical costs per patient-year for clinical events were determined. Based on clinical event rates for patients in the AVERROES trial, medical costs excluding drug costs were estimated for apixaban- and aspirin-treated patient groups.

Results and Conclusions:

Based on AVERROES trial results, among patients with AF unsuitable for warfarin therapy, apixaban use was estimated to be associated with a mean medical cost avoidance of US$735 in a patient-year relative to aspirin. The primary driver was the significant reduction in ischemic stroke rate. The medical cost reduction associated with apixaban use was consistent in sensitivity analyses.

A comparative analysis of models used to evaluate the cost-effectiveness of dabigatran versus warfarin for the prevention of stroke in atrial fibrillation

BACKGROUND

A number of models exploring the cost-effectiveness of dabigatran versus warfarin for stroke prevention in atrial fibrillation have been published. These studies found dabigatran was generally cost-effective, considering well-accepted willingness-to-pay thresholds, but estimates of the incremental cost-effectiveness ratios (ICERs) varied, even in the same setting. The objective of this study was to compare the findings of the published economic models and identify key model features accounting for differences.

METHODS

All aspects of the economic evaluations were reviewed: model approach, inputs, and assumptions. A previously published model served as the reference model for comparisons of the selected studies in the US and UK settings. The reference model was adapted, wherever possible, using the inputs and key assumptions from each of the other published studies to determine if results could be reproduced in the reference model. Incremental total costs, incremental quality-adjusted life years (QALYs), and ICERs (cost per QALY) were compared between each study and the corresponding adapted reference model. The impact of each modified variable or assumption was tracked separately.

RESULTS

The selected studies were in the US setting (2), the Canadian setting (1), and the UK setting (2). All models used the Randomized Evaluation of Long-Term Anticoagulation study (RE-LY) as the main source for clinical inputs, and all used a Markov modelling approach, except one that used discrete event simulation. The reference model had been published in the Canadian and UK settings. In the UK setting, the reference model reported an ICER of UK£4,831, whereas the other UK-based analysis reported an ICER of UK£23,082. When the reference model was modified to use the same population characteristics, cost inputs, and utility inputs, it reproduced the results of the other model (ICER UK£25,518) reasonably well. Key reasons for the different results between the two models were the assumptions on the event utility decrement and costs associated with intracranial haemorrhage, as well as the costs of warfarin monitoring and disability following events. In the US setting, the reference model produced an ICER similar to the ICER from one of the US models (US$15,115/QALY versus US$12,386/QALY, respectively) when modelling assumptions and input values were transferred into the reference model. Key differences in results could be explained by the population characteristics (age and baseline stroke risk), utility assigned to events and specific treatments, adjustment of stroke and intracranial haemorrhage risk over time, and treatment discontinuation and switching. The reference model was able to replicate the QALY results, but not the cost results, reported by the other US cost-effectiveness analysis. The parameters driving the QALY results were utility values by disability levels as well as utilities assigned to specific treatments, and event and background mortality rates.

CONCLUSIONS

Despite differences in model designs and structures, it was mostly possible to replicate the results published by different authors and identify variables responsible for differences between ICERs using a reference model approach. This enables a better interpretation of published findings by focusing attention on the assumptions underlying the key model features accounting for differences.

Does warfarin use impact hospital length of stay? A retrospective study looking at patients treated for atrial fibrillation

The authors received anecdotal practice information from clinicians indicating that when warfarin was initiated in the hospital setting, it may be associated with an increased length of stay (LOS): specifically to achieve a desired minimum international normalized ratio (INR) of 2.0 before discharge in a subset of patients where clinicians perceived follow-up after discharge was not deemed optimal. Given that oral thromboprophylactic anticoagulation with warfarin is the mainstay treatment for the prevention of stroke in atrial fibrillation (AF), the authors decided to look at hospitalized patients from this population to determine if a subset of these patients experienced an increased LOS. The study design entailed a retrospective chart review of consecutive patients admitted to a large, tertiary care, academic center. Patients were included if they were admitted with a primary, secondary, or most responsible diagnosis of paroxysmal or chronic AF. Medical records were audited over an 18-month period (February 1, 2009, to July 31, 2010) to determine the average LOS and to identify patients with a documented prolonged LOS secondary due to subtherapeutic INR at the time of potential discharge. Our final study cohort of 189 patients had an average LOS of 5.2 days (SD = 5.2). However, for eight (4.2%) of these patients discharge was delayed an additional 2.25 days (SD = 1.3) for reasons solely attributed to achieving a therapeutic INR.