Cost-utility analysis of stenting versus endarterectomy in the International Carotid Stenting Study

Abstract

Background: The International Carotid Stenting Study was a multicenter randomized trial in which patients with symptomatic carotid artery stenosis were randomly allocated to treatment by carotid stenting or endarterectomy. Economic evidence comparing these treatments is limited and inconsistent.

Aims: We compared the cost-effectiveness of stenting versus endarterectomy using International Carotid Stenting Study data.

Methods: We performed a cost-utility analysis estimating mean costs and quality-adjusted life years per patient for both treatments over a five-year time horizon based on resource use data and utility values collected in the trial. Costs of managing stroke events were estimated using individual patient data from a UK population-based study (Oxford Vascular Study).

Results: Mean costs per patient (95% CI) were US$10,477 ($9669 to $11,285) in the stenting group (N = 853) and $9669 ($8835 to $10,504) in the endarterectomy group (N = 857). There were no differences in mean quality-adjusted life years per patient (3.247 (3.160 to 3.333) and 3.228 (3.150 to 3.306), respectively). There were no differences in adjusted costs between groups (mean incremental costs for stenting versus endarterectomy $736 (95% CI -$353 to $1826)) or adjusted outcomes (mean quality-adjusted life years gained -0.010 (95% CI -0.117 to 0.097)). The incremental net monetary benefit for stenting versus endarterectomy was not significantly different from zero at the maximum willingness to pay for a quality-adjusted life year commonly used in the UK. Sensitivity analyses showed little uncertainty in these findings.

Conclusions: Economic considerations should not affect whether patients with symptomatic carotid stenosis undergo stenting or endarterectomy.

Keywords: Cost factors; carotid endarterectomy; carotid stenosis; carotid stenting; clinical trial; economics.

Figure 1. Cost-effectiveness acceptability curve showing the probability that stenting is cost-effective vs. endarterectomy at different values of the maximum willingness to pay for a QALY

QALY = quality adjusted life year.

Figure 2. Univariate sensitivity analysis

MI = myocardial infarction. NMB = net monetary benefit. All analyses are as for the base case analysis with univariate adjustment of the parameters listed (see text). Results are point estimates of the incremental net monetary benefit of stenting vs. endarterectomy (circles) and 95% confidence intervals (capped spikes). The incremental net monetary benefit is calculated at a maximum willingness to pay for a QALY of $29 000 (see Supporting Information for results calculated at a maximum willingness to pay for a QALY of $43 000).