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Brief Report
July 5, 2017

Association of Variation in Contrast Volume With Acute Kidney Injury in Patients Undergoing Percutaneous Coronary Intervention

Author Affiliations
  • 1Cardiovascular Division, Washington University School of Medicine, St Louis, Missouri
  • 2Barnes-Jewish Hospital, St Louis, Missouri
  • 3Center for Value and Innovation, Washington University School of Medicine, St Louis, Missouri
  • 4Saint Luke’s Mid America Heart Institute, University of Missouri at Kansas City
JAMA Cardiol. Published online July 5, 2017. doi:10.1001/jamacardio.2017.2156
Key Points

Question  What is the variation in contrast volume and acute kidney injury incidence among US physicians after performing percutaneous coronary intervention?

Findings  In this cross-sectional study involving more than 1.3 million patients who underwent percutaneous coronary intervention, a large variation in acute kidney injury incidence and contrast use was observed among physicians who performed the procedures. There was no evidence that physicians used significantly less contrast in patients at higher risk of acute kidney injury.

Meaning  The variation among physicians and the absence of an adjustment in contrast volume for patients at higher risk for acute kidney injury underscores an important opportunity to reduce acute kidney injury.

Abstract

Importance  Acute kidney injury (AKI) after percutaneous coronary intervention (PCI) is common, morbid, and costly; increases patients’ mortality risk; and can be mitigated by limiting contrast use.

Objective  To examine the national variation in AKI incidence and contrast use among US physicians and the variation’s association with patients’ risk of developing AKI after PCI.

Design, Setting, and Participants  This cross-sectional study used the American College of Cardiology National Cardiovascular Data Registry (NCDR) CathPCI Registry to identify in-hospital care for PCI in the United States. Participants included 1 349 612 patients who underwent PCI performed by 5973 physicians in 1338 hospitals between June 1, 2009, and June 30, 2012. Data analysis was performed from July 1, 2014, to August 31, 2016.

Main Outcomes and Measures  The primary outcome was AKI, defined according to the Acute Kidney Injury Network criteria as an absolute increase of 0.3 mg/dL or more or a relative increase of 50% or more from preprocedural to peak creatinine. A secondary outcome was the mean contrast volume as reported in the NCDR CathPCI Registry. Physicians who performed more than 50 PCIs per year were the main exposure variable of interest. Hierarchical regression with adjustment for patients’ AKI risk was used to identify the variation in AKI rates, the variation in contrast use, and the association of contrast volume with patients’ predicted AKI risk.

Results  Of the 1 349 612 patients who underwent PCI, the mean (SD) age was 64.9 (12.2) years, 908 318 (67.3%) were men, and 441 294 (32.7%) were women. Acute kidney injury occurred in 94 584 patients (7%). A large variation in AKI rates was observed among individual physicians ranging from 0% to 30% (unadjusted), with a mean adjusted 43% excess likelihood of AKI (median odds ratio, 1.43; 95% CI, 1.41-1.44) for statistically identical patients presenting to 2 random physicians. A large variation in physicians’ mean contrast volume, ranging from 79 mL to 487 mL with an intraclass correlation coefficient of 0.23 (interquartile range, 0.21-0.25), was also observed, implying a 23% variation in contrast volume among physicians after adjustment. There was minimal correlation between contrast use and patients’ AKI risk (r = −0.054). Sensitivity analysis after excluding complex cases showed that the physician variation in AKI remained unchanged.

Conclusions and Relevance  Acute kidney injury rates vary greatly among physicians, who also vary markedly in their use of contrast and do not use substantially less contrast in patients with higher risk for AKI. These findings suggest an important opportunity to reduce AKI by reducing the variation in contrast volumes across physicians and lowering its use in higher-risk patients.

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