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28-03-2011 | Stroke | Article

Post-marketing study CAS outcomes a poor reflection of reality


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MedWire News: Carotid artery stenting (CAS) outcomes derived from post-marketing surveillance (PMS) studies are "unlikely" to reflect outcomes in real-world clinical practice, say researchers.

PMS studies are often required by regulatory authorities to address concerns that outcomes achieved in tightly controlled clinical trials may not be replicable in clinical practice. Several trials of CAS devices had strenuous criteria for operator training and involved many highly experienced academic centers, whereas data from PMS studies are thought to be widely generalizable.

"Our data challenge this assumption and suggest that PMS study results may not be representative of the larger population of patients being treated with these devices," say Robert Yeh (Massachusetts General Hospital, Boston, USA) and co-workers.

The team used data from the National Cardiovascular Database Registry-Carotid Artery Revascularization and Endarterectomy (NCDR CARE) registry to compare 3689 CAS patients who were enrolled in a PMS study with 3426 who were not.

They found that PMS participants were significantly less likely to die in hospital than nonparticipants, at 0.3% versus 1.4%, resulting in a lower composite rate of in-hospital death, stroke, or myocardial infarction, at 4.1% versus 5.6%, and a reduced rate of all-cause mortality over the subsequent 2 years.

The difference in in-hospital mortality risk persisted, at a 56% reduction among PMS participants, after adjusting for patient, procedural, and hospital variables that influenced patients' propensity to be included in a PMS study. Subsequent all-cause mortality was a significant 20% lower among PMS participants than nonparticipants.

The reduced mortality risk among PMS participants was largely explained by their neurological history, Yeh et al report in the journal Circulation. PMS participants were significantly less likely than nonparticipants to have a previous cerebrovascular event, at 40.5% versus 59.9%, a recently symptomatic target lesion, at 31.5% versus 58.2%, or acute evolving stroke, at 1.0% versus 3.9%.

The researchers suggest that several factors may have contributed to the difference in outcomes between the PMS participants and nonparticipants. These include the requirement for informed consent to participate in PMS studies, use of off-label procedures in nonparticipants, and the effect of participation on eligibility for reimbursement.

Yeh and team believe that real-world outcomes for CAS probably fall between those of the PMS participants and nonparticipants. They stress the importance of registries such as NCDR CARE for monitoring CAS outcomes and add that "the development of such registries for other novel devices and treatments should be considered."

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Eleanor McDermid