Background:
Carotid endarterectomy (CEA) reduces stroke risk compared to medical therapy alone among patients with asymptomatic carotid stenosis. CEA involves a tradeoff between higher perioperative short-term risks in exchange for a lower long-term risk of stroke. However, overall declines in stroke rates raise concerns that CEA may no longer be a preferred treatment. We examined the effectiveness of CEA compared to medical therapy (MT) among asymptomatic patients in preventing stroke and stroke-death within 5 years of follow-up.
Methods:
We identified Veterans ≥65 years old with carotid stenosis (n=2712 CEA and n=2509 MT patients) who did not have a history of stroke or transient ischemic attack. We propensity score-matched MT patients to CEA patients to control for baseline confounding and used methods to mimic analyses from the Asymptomatic Carotid Stenosis Trial, the last published trial to compare CEA to MT. We accounted for “immortal time” bias by randomizing patients to CEA and MT groups and censoring patients if their actual treatment became inconsistent with the arm in which they were randomized (e.g., patient received CEA, but was randomized to MT). We accounted for the informative censoring by estimating time-dependent inverse probability of censoring weights using measured covariates (demographics and 72 time-varying comorbidities). We computed weighted Kaplan-Meier (KM) curves and estimated the risk of stroke/stroke-death in each group over 5 years of follow-up.
Results:
The observed stroke or death rate (perioperative complications) within 30 days in the CEA arm was 3%. The 5-year risk were similar among patients randomized to CEA 5.5% (95% CI, 4.3%-6.7%) versus MT 7.6% (95% CI,5.9%-9.2%) (risk difference, -2.1%, 95% CI -4%- 0%) with little difference in the KM curves (logrank p=0.2).
Conclusion:
CEA was not superior to MT in a community sample of Veterans after 5 years of follow-up, suggesting that CEA may no longer be the preferred treatment strategy.
Comparative Effectiveness of Carotid Endarterectomy vs Initial Medical Therapy in Patients With Asymptomatic Carotid Stenosis