An analysis of Medicare data indicates that older patients who had a stent placed in the carotid artery by a physician operator who performed less than six of the procedures a year, or if the procedure was conducted early in the operator’s career, had an increased risk of death 30 days after the stent placement, according to a study published in the 28 September 2011 issue of JAMA.
“Carotid stenting is increasingly being used to treat severe carotid atherosclerosis, an important cause of ischaemic stroke. Since approval of the first carotid stent system by the FDA in 2004, use of carotid stenting has more than doubled in Medicare beneficiaries,” the authors wrote.
Despite the promise of this procedure, its increasing use has also raised potential concerns. “Carotid stenting is a technically demanding procedure and earlier studies have demonstrated a substantial learning curve with it,” they said. “…the total number of operators currently performing carotid stenting in routine clinical practice and their overall experiences and outcomes with the procedure remain largely unknown.”
Brahmajee K Nallamothu, University of Michigan Medical School, Ann Arbor, USA, and colleagues conducted a study to examine recent patterns of utilisation and outcomes for carotid stenting in the United States among elderly patients. The researchers used administrative data from fee-for-service Medicare beneficiaries ages 65 years or older who underwent carotid stenting between 2005 and 2007. Among the outcomes the researchers measured were 30-day mortality, stratified by very low, low, medium, and high annual operator volumes (less than 6, 6–11, 12–23, and 24 or more procedures per year, respectively) and treatment early vs. late during an operator’s experience (1st to 11th procedure and 12th procedure or higher).
Analysis of the data identified 24,701 patients who underwent carotid stenting by 2,339 operators. Of these, 11,846 procedures were performed by 1,792 new operators who first performed carotid stenting after a national coverage decision by the Centers for Medicare and Medicaid Services (CMS) in March 2005. Average age of the patients in the study was 76.2 years; 40.2% were women; and 4.3% were black. Overall, 461 patients (1.9%) died within 30 days of their procedure. The median (midpoint) annual operator volume in Medicare beneficiaries during the study period was 3.0 per year. A total of 639 operators (27.3%) performed six or more procedures per year and 272 operators (11.6%) performed 12 or more procedures per year.
The researchers found higher 30-day mortality rates in patients treated by operators with lower annual volumes of carotid stenting, with 30-day mortality rates of 2.5%, 1.9%, 1.6%, and 1.4% across the four categories of volume, from lowest to highest. Compared with patients treated by operators performing 24 or more procedures per year, those treated by operators performing less than six procedures per year had a 1.9 times increased odds of dying within 30 days of the stent placement.
The authors also found higher 30-day mortality in patients treated early vs. late during a new operator’s experience (2.3% vs. 1.4%, respectively). Compared with patients who were their operator’s 12th procedure or higher, those who were among their operator’s first 11 procedures had a 1.7 times higher odds of dying within 30 days of the procedure.
“In conclusion, many physicians have begun performing carotid stenting in Medicare beneficiaries during recent years, although most operators appear to have developed limited experience with the procedure over time. This finding is important since adjusted outcomes following the procedure are worse among very low-volume operators and early during an operator’s experience. Given limitations of these data, caution should be exerted when using our findings to set specific targets for operator experience. Nevertheless, collecting more detailed data about operator experience during the early dissemination of new procedures, like carotid stenting, may help optimise outcomes,” the authors wrote.
In an accompanying editorial, Ethan A Halm, University of Texas Southwestern Medical Center, Dallas, comments on the findings of this study.
“From the perspective of a patient or referring physician, there is no easy way to know whether a procedure will be performed by a skilled operator. In the absence of knowing a physician’s actual clinical outcomes or experience, referrals to most carotid angioplasty with stenting proceduralists may result in suboptimal outcomes because most are very low-volume operators who are early in the learning curve. This problem is likely to get worse before it gets better because an increasing number of cardiologists, interventional radiologists, and surgeons are performing carotid artery stenting procedures. ‘Selectively referring’ patients to the most experienced, highest-volume clinicians would be optimal but is often unrealistic. Pragmatically, the least experienced operators should be ‘selectively avoided’ unless they can provide acceptable outcome data or other convincing evidence of proficiency.”