1053 — Institutional Variation in Acute Kidney Injury Following Cardiac Catheterization: Insights from the National VA CART Program

Matheny ME, TVHS VA, Vanderbilt University; Maddox TM, Denver VA, University of Colorado; Plomondon ME, Denver VA, University of Colorado; Siew ED, TVHS VA, Vanderbilt University; Resnic FS, Lahey Clinic; MacKenzie TA, White River Junction VA, Dartmouth College; Tsai T, Kaiser Permanente, Denver VA; Speroff T, TVHS VA, Vanderbilt University; Sandho A, Rumsfeld JS , Denver VA, University of Colorado; Brown JR, White River Junction VA, Dartmouth College

Objectives:
To evaluate hospital variation and simulate prospective surveillance for risk adjusted institutional outliers for acute kidney injury following cardiac catheterization within a retrospective national Veteran cohort

Methods:
National retrospective data from CART and CDW were integrated for patients receiving cardiac catheterization from 1/1/2009 to 09/31/2013. The outcome was Acute Kidney Injury (AKI) Network Stage 1 or greater AKI determined using the most recent creatinine in the prior year and 7 days following the procedure. Risk adjusted sequential probability ratio testing (RA-SPRT) was performed in each year for each center using an alerting threshold of an odds ratio (OR) of 2.0 and 0.5, alpha 0.05, and beta 0.1. Risk adjustment was conducted by developing sequential logistic regression risk models from 12 months prior to the scored month using 42 pre- and peri- procedural variables from among patient demographics, laboratory tests, IV fluids, medications, administrative codes, and the proportion of missing post-procedural creatinine per site/month. Observed/Expected (O/E) ratios with 95% confidence intervals for the study period were calculated. This analysis was performed using an open source Java statistical engine that supports prospective surveillance and verified using SAS 9.4.

Results:
A total of 71 institutions and 111,995 catheterizations were analyzed for risk-adjusted AKI. The overall AKI event rate was 14.2%. 22 institutions had a statistically significantly lower-than-expected O/E, 38 were within expectation, and 11 had a higher-than-expected O/E for all years. The RA-SPRT analysis revealed that a total of 21, 7, 4, 2, and 0 institutions were at < 0.5 OR and 8, 8, 2, 2, and 1 institutions were at > 2.0 OR for risk-adjusted AKI events in 1, 2, 3, 4, or 5 calendar years, respectively.

Implications:
Institutional variation for AKI following cardiac catheterization was substantial after extensive risk-adjustment using electronic health record and clinical registry data. These analyses are hypothesis generating and warrant additional exploration into the possible causes of the variation that were in patient and clinical workflow factors that were not captured in the risk adjustment.

Impacts:
Further exploration as to the causes of variation is warranted and may offer opportunities for quality improvement initiatives to standardize care.