Impact of Annual Operator and Institutional Volume on Percutaneous Coronary Intervention Outcomes: A 5-Year United States Experience (2005 - 2009)

Study Questions:

What is the relationship between operator and institutional volume among patients undergoing percutaneous coronary intervention (PCI)?


The authors assessed the relationship between volume and outcome using the Healthcare Cost and Utilization Project’s Nationwide Inpatient Sample between 2005-2009. Subjects were identified by International Classification of Diseases, 9th Revision, procedure codes. Annual operator and institutional volumes were calculated using unique identification numbers and then divided into quartiles. The primary outcome for this study was in-hospital mortality, and secondary outcome was a composite of in-hospital mortality and periprocedural complications.


The analysis was performed on 457,498 PCIs, which represented 2,243,209 PCIs performed in the United States during the study period. Median operator PCI volume declined from 53 (2005) to 33 annually (2009). Overall in-hospital all-cause mortality was 1.08%, and the overall complication rate was 7.10%. The annual procedural volume in each quartile was ≤15, 16-44, 45-100, and >100. Crude mortality rates significantly declined with volume (1.68%, 1.15%, 0.87%, and 0.59% in first [≤15 PCIs/year], second, third, and fourth quartile of operator volume, respectively). Similarly, complication rates were 10.12%, 7.17%, 5.96%, and 5.19% with increasing quartiles of operator volume. These differences remained significant after adjusting for variation in patient mix and complexity. Operators in the higher quartiles witnessed a significant reduction in length of hospital stay (LOS) and cost of hospitalization (p < 0.001).


The authors concluded that there is a strong association between operator volume and outcome of PCI.


This study highlights two important points. First, it re-demonstrates the strong association between operator volume and outcome. Second, it highlights the fact that there are a lot of procedures being performed by low-volume operators. The fact that a quarter of operators in the country performed <15 procedures a year is particularly alarming and almost belies belief. This study reflects practice pattern prior to 2009, and PCI volumes have declined even further since then, suggesting that the number of low-volume operators might be even higher. These findings invoke a need for greater scrutiny by institutions on their operator procedural volume, and greater oversight of low-volume operators.

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