Is the Cost-Effectiveness of Stroke Thrombolysis Affected by Proportion of Stroke Mimics?

Background and Purpose- Differentiating ischemic stroke patients from stroke mimics (SM), nonvascular conditions which simulate stroke, can be challenging in the acute setting. We sought to model the cost-effectiveness of treating suspected acute ischemic stroke patients before a definitive diagnosis could be made. We hypothesized that we would identify threshold proportions of SM among suspected stroke patients arriving to an emergency department above which administration of intravenous thrombolysis was no longer cost-effective. Methods- We constructed a decision-analytic model to examine various emergency department thrombolytic treatment scenarios. The main variables were proportion of SM to true stroke patients, time from symptom onset to treatment, and complication rates. Costs, reimbursement rates, and expected clinical outcomes of ischemic stroke and SM patients were estimated from published data. We report the 90-day incremental cost-effectiveness ratio of administering intravenous thrombolysis compared with no acute treatment from a healthcare sector perspective, as well as the cost-reimbursement ratio from a hospital-level perspective. Cost-effectiveness was defined as a willingness to pay <$100 000 USD per quality adjusted life year gained and high cost-reimbursement ratio was defined as >1.5. Results- There was an increase in incremental cost-effectiveness ratios as the proportion of SM cases increased in the 3-hour time window. The threshold proportion of SM above which the decision to administer thrombolysis was no longer cost-effective was 30%. The threshold proportion of SM above which the decision to administer thrombolysis resulted in high cost-reimbursement ratio was 75%. Results were similar for patients arriving within 0 to 90 minutes of symptom onset as compared with 91 to 180 minutes but were significantly affected by cost of alteplase in sensitivity analyses. Conclusions- We identified thresholds of SM above which thrombolysis was no longer cost-effective from 2 analytic perspectives. Hospitals should monitor SM rates and establish performance metrics to prevent rising acute stroke care costs and avoid potential patient harms.