Meta-analysis: Operator Volume Affects Clinical Outcomes After PCI
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Patients of interventional cardiologists who perform few annual percutaneous coronary interventions (PCIs) have higher rates of mortality and major adverse cardiovascular events (MACE) than those treated by higher-volume operators, according to a systematic review and meta-analysis published online June 17, 2014, ahead of print in Circulation: Cardiovascular Quality and Outcomes.
However, there was no clear cutoff for what constitutes adequate volume.
| Methods |
| Researchers led by Robert W. Yeh, MD, MSc, of Massachusetts General Hospital (Boston, MA), examined 23 studies published between 1996 and 2009 that reported on operator-specific PCI volume and patient outcomes. The studies included 15,907 operators at 2,456 centers with a mean patient follow-up of 2.8 years. |
| Studies were grouped by the degree to which they controlled for areas of confounding and potential bias, and their quality was rated as fair, good, high, or very high. |
Higher Volume, Lower Mortality
Of the 23 studies, 14 (61%) evaluated mortality, 7 (30%) looked at MACE, and 2 (9%) included angiographic success.
Among 6 ‘high’ or ‘very high’ quality studies that evaluated mortality, 4 showed a pattern of reduced mortality with increased volume of PCI. In these studies, compared with patients of low-volume operators (≤ 2 annual procedures performed), patients of operators performing 11 or more PCIs per year had reductions in mortality as high as 57% (95% CI 0.21-0.83). Analysis restricted to ‘very high’ and ‘high’ quality studies demonstrated a trend toward fewer deaths (OR 0.90; 95% CI 0.79-1.01) for high- vs low-volume operators with heterogeneity among studies (P = .0256).
In a random effects model, a decrease in MACE also was seen when high- and low-volume operators were compared (OR 0.62; 95% CI 0.40-0.97), with heterogeneity (P < .0001) and no publication bias (P = .88).
There was considerable variability in the definition of volume across the studies, including low-volume cutoffs ranging from less than 25 to 100 PCIs per year and high-volume cutoffs ranging from more than 50 to 270 per year.
Where to Draw the Line?
Current ACCF/AHA/SCAI clinical competency guidelines recommend that interventional cardiologists perform a minimum of 50 annual procedures averaged over a 2-year period.
The guidelines further state: “The writing committee believes operators performing < 50 PCIs/year should not be denied privileges or excluded from performing coronary interventions based solely on their procedural volume. In instances where operators are performing < 50 PCIs annually, the writing committee strongly encourages both institutions and operators to carefully assess whether their performance is adequate to maintain competence.”
Dr. Yeh and colleagues say their findings “support the recommendations for operators to achieve a higher annual PCI volume but do not clearly endorse value 50 as the appropriate threshold.”
Furthermore, they write that heterogeneity in the quality and design of studies “preclude[s] the ability to definitively evaluate the magnitude of this effect or the existence of a threshold above which volume differences are no longer meaningful.” They add that analysis of volume as a continuous variable in future studies may aid in identifying a threshold effect, should one exist.
However, the study authors say their findings support recommendations for achieving higher annual PCI volumes by increasing regionalization and consolidation. Of particular interest in the current economic climate, they say, is that the growth of PCI centers has outpaced population expansion as well as declining rates of CAD. “Recognizing that 61% of PCI operators in 2008, accounting for 30% of all PCIs performed nationally, performed ≤ 40 Medicare fee-for-service PCIs argues for the consolidation rather than addition of cardiac catheterization laboratories and for further regionalization of PCI care,” Dr. Yeh and colleagues contend.
‘Questionable… and Murky’
However, David L. Brown, MD, of Washington University School of Medicine (St Louis, MO), said in an email with TCTMD that the paper “is a good example of the situation where a study demonstrates statistical significance but the clinical significance is questionable and the policy implications are even more murky.”
While there clearly is a general relationship between average PCI volume and outcome, the relationship is linear, making it unclear where to draw the line that demarcates low- vs high-volume operators, he said, adding that “there are individual exceptions; some low-volume operators are excellent and some high-volume operators are mediocre.”
Dr. Yeh and colleagues acknowledge that many potential variables could impact interpretation of the relationship between operator volume and outcomes. Among these are primary PCI vs procedures performed on more stable patients, and the participation of trainees in procedures at academic medical centers.
Sources:
1. Strom JB, Wimmer NJ, Wasfy JH, et al. Association between operator procedure volume and patient outcomes in percutaneous coronary intervention: a systematic review and meta-analysis. Circ Cardiovasc Qual Outcomes. 2014;Epub ahead of print.
2. Harold JG, Bass TA, Bashore TM, et al. ACCF/AHA/SCAI 2013 update of the clinical competence statement on coronary artery interventional procedures: a report of the American College of Cardiology Foundation/American Heart Association/American College of Physicians Task Force on Clinical Competence and Training (Writing Committee to Revise the 2007 Clinical Competence Statement on Cardiac Interventional Procedures). J Am Coll Cardiol. 2013;62:357-396.
Disclosures:
- Drs. Yeh and Brown report no relevant conflicts of interest.
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L.A. McKeown is a Senior Medical Journalist for TCTMD, the Section Editor of CV Team Forum, and Senior Medical…
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