SCAR Rule Shows Potential for Identifying Patients' Perioperative Risks With CAS Versus CEA

December 1, 2013—A clinical rule, SCAR (Sex, Contralateral Occlusion, Age, and Restenosis), is potentially useful to identify patients in whom carotid artery stenting (CAS) has a similar risk of perioperative stroke or death to carotid endarterectomy (CEA), concluded a study by Emmanuel Touzé, MD, et al, which was published in Stroke (2013;44:3394–3400). The investigators conducted a systematic review of observational studies with validation in randomized trials.

The investigators stated that the background of the study is that, compared with CEA, CAS is associated with a higher risk of procedural stroke or death, especially in patients with symptomatic stenosis. However, after the perioperative period, the risk is similar with both treatments, suggesting that CAS could be an acceptable option in selected patients.

As summarized in Stroke, the investigators performed systematic reviews of observational studies on procedural risks of CEA or CAS and extracted data on nine predefined risk factors (age, contralateral carotid occlusion, coronary artery disease, diabetes mellitus, sex, hypertension, peripheral artery disease, and type and side of stenosis). They calculated pooled relative risks of procedural stroke or death. Factors with differential effects on risk of CAS versus CEA were identified by interaction tests and used to derive a rule. The rule was tested using individual patient data from randomized trials of CAS versus CEA from the Carotid Stenting Trialists’ Collaboration (CSTC).

The investigators identified 170 studies. The effects of sex, contralateral occlusion, age, and restenosis (SCAR) on the procedural risk of stroke or death differed. Patients with contralateral occlusion or restenosis and women older than 75 years were at relatively low risk with CAS (SCAR negative), with all others being high risk (SCAR positive). Among the 3,049 patients in the CSTC validation, 694 patients (23%) were SCAR negative. The pooled relative risk of procedural stroke and death with CAS versus CEA was 0.93 (0.49–1.77; P = .83) in SCAR-negative and 2.41 (1.68–3.45; P < .0001) in SCAR-positive patients (P interaction = .05), reported the investigators.