Cost Effectiveness of Interhospital Transfer for Mechanical Thrombectomy of Acute Large Vessel Occlusion Stroke: Role of Predicted Recanalization Rates

Background: Emergency interhospital transfer of patients with stroke with large vessel occlusion to a comprehensive stroke center for mechanical thrombectomy is resource-intensive and can be logistically challenging. Imaging markers may identify patients in whom intravenous thrombolysis (IVT) alone is likely to result in thrombus resolution, potentially rendering interhospital transfers unnecessary. Here, we investigate how predicted probabilities to achieve IVT-mediated recanalization affect cost-effectiveness estimates of interhospital transfer.

Methods: We performed a health economic analysis comparing emergency interhospital transfer of patients with acute large vessel occlusion stroke after administration of IVT with a scenario in which patients also receive IVT but remain at the primary hospital. Results were stratified by clinical parameters, treatment delays, and the predicted probability to achieve IVT-mediated recanalization. Estimated 3-month outcomes were combined with a long-term probabilistic model to yield quality-adjusted life years (QALYs) and costs. Uncertainty was quantified in probabilistic sensitivity analyses.

Results: Depending on input parameters, marginal costs of interhospital transfer ranged from USD -61 366 (cost saving) to USD +20 443 and additional QALYs gained from 0.1 to 3.0, yielding incremental cost-effectiveness ratios of <USD 0 (dominant) to USD 310 000 per QALY. For some elderly patients with moderate or severe stroke symptoms treated in a remote primary stroke center, transfer was unlikely to be cost effective at a willingness-to-pay threshold of USD 100 000 and 50 000 per QALY (20% and 1%, respectively) if the predicted probability to achieve IVT-related recanalization was high. On the other hand, in some younger patients, the analysis yielded incremental cost-effectiveness ratio estimates below USD 20 000 per QALY independent of the predicted recanalization rate.

Conclusions: Predicted probabilities to achieve IVT-mediated recanalization significantly affect the cost-effectiveness of interhospital transfer for MT, in particular in elderly patients with moderate or severe stroke symptoms. However, high predicted recanalization rates alone do not generally imply that patients should not be considered for transfer.