Haptoglobin Administration in Cardiovascular Surgery Patients: Its Association With the Risk of Postoperative Acute Kidney Injury

BACKGROUND: Acute kidney injury (AKI) often occurs after cardiac surgery. During cardiac surgery, plasma free hemoglobin (fHb) would increase due to hemolysis. Since plasma fHb is thought to be nephrotoxic, haptoglobin, which is an fHb scavenger, may have the potential to prevent postoperative AKI (pAKI). However, there have been few studies in which the association of intraoperative administration of haptoglobin with the incidence of AKI after cardiac surgery was assessed. METHODS: This study was a retrospective observational study to assess the independent association of intraoperative administration of haptoglobin with the incidence pAKI in cardiac surgery patients. We screened cardiac surgery patients who required cardiopulmonary bypass from 2008 to 2015. We excluded patients who required renal replacement therapy preoperatively. We also excluded patients in whom descending aortic replacement was performed. pAKI was defined according to AKI Network criteria. A propensity score-matched model was used to adjust confounders. For sensitive analysis, we further developed a logistic regression model. RESULTS: We included 1326 patients in this study. The incidence of AKI in the total cohort was 25.5% (338 patients). Haptoglobin was administered in 260 patients (19.6%). In the crude cohort, the incidence of AKI in patients with haptoglobin administration was 24.6%, which was not significantly different from the incidence of 25.7% in those without haptoglobin administration (P = .72; odds ratio, 0.94 [95% confidence interval, 0.69-1.29]). After propensity score matching, we had 249 patients in each group (for a total of 498 patients). In this propensity score-matched cohort, the incidence of AKI in patients with haptoglobin administration was 22.5%, which was significantly lower than the incidence of 30.9% in those without haptoglobin administration (P = .033; odds ratio, 0.65 [0.43-0.97]). In our logistic regression model for the risk of pAKI, haptoglobin administration was independently associated with decreased risk of AKI (P = .029; adjusted odds ratio, 0.54 [0.31, 0.93]). CONCLUSIONS: In this hypothesis-generating, single-center retrospective observational study, intraoperative administration of haptoglobin was independently associated with lower risk of AKI after cardiovascular surgery.