Outcomes of PCI in Relation to Procedural Characteristics and Operator Volumes in the United States
Key result
Low PCI operator volume linked to ~16% higher in-hospital mortality vs. high-volume operators.
- OR 1.16
- 95% CI 1.12-1.21
- n=3,747,866
Why the study?
Professional guidelines reduced the recommended minimum annual PCI procedures per operator to 50, but operator volume patterns and associated outcomes since this change are unknown.
Does low PCI operator volume increase in-hospital mortality in patients undergoing percutaneous coronary intervention?
Key Points
- To evaluate annual PCI operator volumes, characterize operator practice patterns, and examine the association between annual operator procedure volume and clinical outcomes, including in-hospital mortality.
- Analyzed 3,747,866 PCI procedures performed by 10,496 operators across 1,584 hospital sites using the national NCDR CathPCI registry between July 1, 2009, and March 31, 2015.
- Categorized operators by annual volume into low (<50 PCIs/year), intermediate (50–100 PCIs/year), and high (>100 PCIs/year) groups based on professional guideline thresholds.
- Assessed risk-adjusted associations between operator volume categories and in-hospital mortality, post-PCI bleeding within 72 hours, and new requirement for dialysis.
- Among evaluated operators, 44% (4,628 operators) performed <50 PCIs/year, with a median overall volume of 59 annual procedures (25th, 75th percentiles: 21, 106).
- Unadjusted in-hospital mortality was 1.86% for low-volume, 1.73% for intermediate-volume, and 1.53% for high-volume operators.
- Adjusted in-hospital mortality was significantly higher for low-volume (adjusted OR 1.16, 95% CI 1.12–1.21) and intermediate-volume operators (adjusted OR 1.05, 95% CI 1.02–1.09) compared with high-volume operators, along with higher adjusted risk for new dialysis but no significant difference in post-PCI bleeding.
Study Design
Type
Cohort (n=3,747,866)
Multicenter
Yes
Structured PICO
Does low PCI operator volume increase in-hospital mortality in patients undergoing percutaneous coronary intervention?
P
Population
3,747,866 percutaneous coronary interventions performed by 10,496 operators across the United States evaluated to determine the relationship between operator volume and in-hospital outcomes.
E
Exposure
Low PCI operator volume (<50 procedures/year)
C
Comparator
High PCI operator volume (>100 procedures/year)
O
Outcome
In-hospital mortalityhard clinical
Main Result
Odds Ratio: 1.16 (95% CI 1.12–1.21)
Absolute Event Rate: 1.86% vs 1.48%
Limitations
- Retrospective analysis subject to unmeasured confounding and post hoc bias
- Lack of variables approximating overall operator experience such as years in practice
- Undercounting of procedures for operators who also practice at non-CathPCI participating hospitals (e.g., Veterans Administration hospitals)
- Retrospective analysis subject to unmeasured confounding
- Lack of variables to approximate overall experience like years in practice
- Undercounting of procedure volumes for operators performing PCIs at non-participating hospitals (e.g., VA hospitals)
Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“Our analysis shows that there is still a relationship between volume and outcome; however, that relationship has significantly attenuated, such that the differences are actually quite small. So it appears that we are getting to a point where volume is a little less important than it used to be in the past. Having said that, the worrisome thing we found is that 44% of operators are doing less than the recommended number of procedures, despite the fact that the bar was lowered.”
“Low-volume operators performed a disproportionate number of emergency PCIs and primary PCIs for STEMI, suggesting that they might perform an important role in maintaining access to PCI.”
Implication
A substantial proportion of US operators perform <50 PCIs per year, and treatment by these low-volume operators is associated with a modest but significantly higher risk-adjusted in-hospital mortality.
Abstract
Background Professional guidelines have reduced the recommended minimum number to an average of 50 PCI procedures performed annually by each operator. Operator volume patterns and associated outcomes since this change are unknown. Objectives To describe PCI operator procedure volumes; characteristics of low-, intermediate-, and high-volume operators; and the relationship between operator volume and clinical outcomes in a large, contemporary, nationwide sample Methods Using data from the nationally representative NCDR CathPCI registry collected between July 1, 2009 and March 31, 2015, we examined operator annual PCI volume. We divided operators into low- (< 50 PCIs/year), intermediate- (50–100 PCIs/year), and high-volume (> 100 PCIs/year) groups, and determined the adjusted association between annual PCI volume and in-hospital outcomes, including mortality. Results The median number of annual procedures performed per operator was 59 (25th, 75th percentiles: 21, 106); 44% of operators performed < 50 PCI procedures/year. Low-volume operators more frequently performed emergency and primary PCI procedures and practiced at hospitals with lower annual PCI volumes. Unadjusted in-hospital mortality was 1.86% for low-volume operators, 1.73% for intermediate-volume operators, and 1.53% for high-volume operators. The adjusted risk of in-hospital mortality was higher for PCI procedures performed by low- and intermediate-volume operators compared with those performed by high-volume operators (adjusted OR 1.16, 95% CI 1.12–1.21 for low vs. high; adjusted OR 1.05, 95% CI 1.02–1.09 for intermediate vs. high volume) as was the risk for new dialysis post PCI. No volume relationship was seen for post-PCI bleeding. Conclusions Many PCI operators in the U.S. are performing fewer than the recommended number of PCI procedures annually. Though absolute risk differences are small and may be partially explained by unmeasured differences in case mix between operators, there remains an inverse relationship between PCI operator volume and in-hospital mortality that persisted in risk-adjusted analyses.
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Cite This Study
Fanaroff et al. (2017) conducted a cohort in Patients undergoing percutaneous coronary intervention (PCI) (n=3,747,866). Low PCI operator volume (<50 procedures/year) vs. High PCI operator volume (>100 procedures/year) was evaluated on In-hospital mortality (OR 1.16, 95% CI 1.12-1.21). Low PCI operator volume (<50 procedures/year) was associated with significantly higher risk-adjusted in-hospital mortality compared to high-volume operators (>100 procedures/year) (OR 1.16).