T. N. Coaston1, J. Curry1, A. Valdlakonda1, C. Branche1, K. Ali1, N. Le1, A. Verma1, P. Benharash1 1David Geffen School of Medicine at UCLA, Cardiac Surgery, Los Angeles, CALIFORNIA, USA
Introduction:
Acute kidney injury (AKI) is a common complication following cardiac surgery. Despite its prevalence, factors associated with AKI remain poorly understood. In this national study, we evaluated center-level variation in incidence of AKI after elective cardiac surgery.
Methods:
All adult patients undergoing elective coronary artery bypass graft (CABG) or valve operations were identified in the 2010 to 2020 National Inpatient Sample. Multilevel mixed-effects models were utilized to rank hospitals based on risk-adjusted rates of AKI. The interclass coefficient (ICC) was used to estimate the level of variation attributable to hospital-level characteristics. High AKI centers (HAC) were defined as those within the highest decile of estimated AKI rate. Patients undergoing cardiac surgery at an HAC comprised the HAC cohort (others: non-HAC).
Multivariable regression models were developed to evaluate the association between HAC status and in-hospital mortality, perioperative complications, length of stay (LOS), and hospitalization costs.
Results:
Of 1,677,020 hospitalizations, 5.4% received their operation at an HAC. Compared to Non-HAC, HAC were more likely to be non-teaching centers (25.5% vs 18.3%; p <0.05) and served a larger proportion of non-white patients (21.0 vs 16.2%; p<0.05). The ICC demonstrates 13% of the observed variation in AKI was due to hospital-level factors (Figure 1A). Additionally, HAC had higher rates of AKI (31.6 vs 12.0%, p<0.05), more often underwent isolated CABG (48.0% vs 41.7%), and less frequently received single valve operations (38.0.% vs 44.2%; p<0.05) compared to non-HAC.
After adjustment, receiving cardiac surgery at an HAC was associated with increased odds of respiratory (Adjusted Odds Ratio [AOR] 1.86, 95% Confidence Interval [CI] 1.69-2.04; Figure 1B), infectious (AOR 1.50, 95% CI 1.34-1.67), and cardiac complications (AOR 1.20, 95% CI 1.13-1.29). Additionally, HAC was associated with higher odds of in-hospital mortality (AOR 1.33, 95% CI 1.18-1.49), as well as incremental increases in LOS (β +0.67 [Days], 95% CI 0.51-0.83) and hospitalization costs (β +$2398, 95% CI $1053-$3743).
Finally, non-White race (AOR 1.45, 95% CI 1.41-1.50) and Medicare insurance (AOR 1.16, 95% CI 1.12-1.20) were associated with increased odds of experiencing a perioperative AKI.
Conclusion:
In the present analysis, we demonstrated significant hospital level variation in perioperative AKI following cardiac surgery. HAC were additionally associated with inferior clinical outcomes and increased resource utilization. Notably, HAC served a higher portion of minority patients suggesting possible contribution to racial disparities. Future study is required to ascertain the drivers behind the observed variation to ultimately maximize care value.
