Meta-analysis: Less Stroke, Death After Carotid Stenting with Higher Operator Volume

Download this article's Factoid (PDF & PPT for Gold Subscribers)


In patients undergoing carotid artery stenting (CAS) in a clinical trial setting, the risk of stroke and death at 30 days is lower when operators perform at least 6 procedures annually, according to a meta-analysis published online December 17, 2013, ahead of print in Stroke. Cumulative lifetime operator experience, however, did not affect outcomes.

Researchers led by Jean-Louis Mas, MD, of Hôpital Sainte-Anne (Paris, France), looked at 1,546 patients with recently symptomatic moderate or severe carotid stenosis who were randomized to CAS as part of the Carotid Stenting Trialists’ Collaboration, a pooled group of 3 trials (EVA-3S, SPACE, and ICSS) each with minimum experience requirements of ≥ 5 CAS procedures annually for operator qualification. About half (49.3%) of patients were at least 70 years and 71.5% were men.

Overall, 7.8% (n = 120) of patients suffered stroke or death within 30 days. While the 30-day risk of stroke or death was not associated with lifetime operator experience (P = 0.8) or lifetime experience excluding the carotid (P = 0.7), it was affected by annual in-trial experience (table 1).

Table 1. Adjusted 30-day Risk of Stroke or Death Based on Operator Experience

Annual In-trial Operator Volume

Events

Adjusted RR (95% CI)

> 5.6 Procedures

5.1%

-

3.2-5.6 Procedures

8.4%

1.93 (1.14-3.27)

≤ 3.2 Procedures

10.1%

2.30 (1.36-3.87)


Crude relative risk assessments also showed increased risk of stroke or death in the low- and intermediate-volume operator groups.

Regarding lifetime procedural experience, the 30-day risk of stroke or death was 9.1% with a high volume operator (> 37 procedures), 7.4% with an intermediate-volume operator (17-37 procedures), and 7.9% with a low-volume operator (< 17 procedures). Compared with high-volume operators, intermediate- (RR 0.82; 95% CI 0.47-1.43) and low-volume operators (RR 0.8; 95% CI 0.51-1.50) were associated with similar 30-day stroke and death outcomes.

There were no differences in outcomes across the 3 time periods of the meta-analysis or when the procedures were supervised or unsupervised.

In-trial Setting Limits Interpretation

Because the lowest event rates were seen with operators who performed at least 6 annual CAS procedures, only centers where such rates are possible for operators should even offer the procedure, the authors write.

In an e-mail communication with TCTMD, Ian C. Gilchrist, MD, of Hershey Medical Center (Hershey, PA), said, “Physicians chosen to participate in clinical trials are not representative of the general population of physicians in practice. How one takes observations generated from the controlled environment of clinical trials and projects that into general clinical guidelines such as ‘6 CAS’ procedures per year is a leap of faith.”

The authors did note that limiting the analysis to in-trial procedures could have led to underestimation of annual CAS volume. However, they argue that misclassification of an operator as high-, intermediate-, or low-volume would likely not differ between those groups, “particularly in those with low in-trial volume.”

Dr. Gilchrist said that in spite of the limited interpretation of the study, the underlying message that increased annual volume correlates with better outcomes is likely a sound one. “It is only logical that a practiced operator will have better outcomes, but whether it is 6 per year or some other number is difficult to ordain based on this analysis,” he observed.

Study Details

The median operator lifetime experience was 27 CAS procedures and 100 stenting procedures excluding the carotid. The median annual in-trial operator volume was 4.3 procedures with tertiles of ≤ 3.2, 3.2 to 5.6, and > 5.6 procedures. Stenting procedures were performed under supervision in 38.8% of patients in EVA-3S, 8.6% in SPACE, and 12.0% in ICSS. CAS procedures were performed by a single operator in 60% of centers and by 2 operators in 26% of centers.

 


Source:
Calvet D, Mas JL, Algra A, et al. Carotid stenting: Is there an operator effect? A pooled analysis from the Carotid Stenting Trialists’ Collaboration. Stroke. 2013;Epub ahead of print.

 

 

Related Stories:

Meta-analysis: Less Stroke, Death After Carotid Stenting with Higher Operator Volume

In patients undergoing carotid artery stenting (CAS) in a clinical trial setting, the risk of stroke and death at 30 days is lower when operators perform at least 6 procedures annually, according to a meta analysis published online December 17,
Disclosures
  • Drs. Mas and Gilchrist report no relevant conflicts of interest.

Comments