Specialty (if any): Cardiac Surgery

Keywords: Acute Kidney Injury, Quality, Disparities

Background: Acute kidney injury (AKI) is a frequent complication following cardiac surgery. However, factors associated with AKI remain poorly understood. In this national study, we evaluated center-level variation in incidence of AKI after elective cardiac surgery.

Objective: The present study used a contemporary, nationally representative cohort of U.S. hospitalizations to evaluate the presence of center-level variation in the development of AKI after elective cardiac surgery.

Methods: Adult patients undergoing elective coronary artery bypass graft or valve operations were identified in the 2010-2020 National Inpatient Sample. Multilevel mixed-effects models were utilized to rank hospitals based on estimated rate of AKI. The interclass coefficient (ICC) was used to estimate the level of variation attributable to hospital factors. High AKI centers (HAC) were defined as those within the highest decile of estimated AKI rate. The association between HAC status, in-hospital mortality, perioperative complications, length of stay, and hospitalization costs were further analyzed.

Results: Of 1,324,083 hospitalizations, 4.9% received their operation at an HAC. Compared to Non-HAC, HAC had lower annual cardiac case volume (62 [40-115] vs 145 [80-265] cases; p < 0.001) and served a larger proportion of non-White patients (20.0 vs 15.1%; p<0.001). After adjustment, HAC was associated with increased odds of respiratory (Adjusted Odds Ratio [AOR] 1.72, 95% Confidence Interval [CI] 1.57-1.90), infectious (AOR 1.57, 95% CI 1.40-1.76), and cardiac complications (AOR 1.27, 95% CI 1.18-1.36). Additionally, HAC was associated with incremental increase in hospitalization costs (β +$4151, 95% CI $2305-$5997).

Conclusions: We demonstrated significant hospital level variation in perioperative AKI. HAC were associated with inferior clinical outcomes and increased resource utilization. Notably, HAC served a higher portion of minority patients suggesting a possible contribution to racial disparities.