Effectiveness and safety of extracranial carotid stent placement: a nationwide self-controlled case-series study

Carotid angioplasty and stent (CAS) placement has emerged as an attractive revascularization strategy for patients with internal carotid artery stenosis. However, the effectiveness and safety of CAS were not fully evaluated, mainly because of methodological difficulties in finding an appropriate comparison group.

Patients who underwent CAS were identified from Taiwan's National Health Insurance claims database between 2005 and 2008. The incidence rate of ischemic stroke after CAS was compared with that of the year prior to the procedure using a self-controlled case series analysis and a conditional Poisson regression model. Logistic regression was conducted to identify factors associated with poor outcome.

A total of 1258 patients who had undergone CAS were included, and 73 cases (5.8%) of death or ischemic stroke occurred during the index hospitalization. Within 1 year after CAS, 74 patients died and 80 experienced an ischemic stroke. Of the 1184 patients who were followed for 360 days, the rate ratio for ischemic stroke decreased to 0.21 (95% CI: 0.08-0.51) between 31 and 180 days, and 0.10 (95% CI: 0.03-0.32) between 181 and 360 days. Statin therapy was associated with a reduced risk of death or ischemic stroke in the 1(st) month (odds ratio of 0.53; 95% CI: 0.32-0.90). Conversely, the use of nonsteroidal anti-inflammatory agents, possibly histamine-2 receptor blockers, and CAS performed by low-volume operators were associated with a twofold increased risk.

CAS reduced the long-term risk for ischemic stroke. Self-controlled case series analysis might be an appropriate design for evaluating device safety and effectiveness.