Risk Factors for Polymyxin B-associated Acute Kidney Injury in Patients with Severe Gram-Negative Bacterial Infections

Background: The occurrence of polymyxin B-associated kidney injury (AKI) has been reported in recent years. The purpose of this study was to investigate the risk factors for polymyxin B-associated AKI and renal function recovery in patients with severe gram-negative bacterial infections. Methods: We conducted a retrospective review of all severe gram-negative bacterial infection patients treated with polymyxin B admitted to Nanjing Drum Tower Hospital, a tertiary hospital in Nanjing City, China, between December 2018 and May 2021. Based on the new onset of AKI within 1 week after polymyxin B treatment, patients were divided into two groups: the AKI group and the non-AKI group. Among the AKI group, the patients were divided into an AKI recovery group and a nonrecovery AKI group according to the recovery of renal function within one week of polymyxin B discontinuation. Clinical manifestations, laboratory findings, treatments and outcomes in these patients were collected and analysed. Results: A total of 188 cases were included. There were 87 cases in the AKI group (46.3%) and 101 cases in the non-AKI group (53.7%). Compared with the non-AKI group, the proportions of hypertension, shock and bacteremia were significantly higher in the AKI group (P < 0.05). In the AKI group, the platelet count was significantly decreased (P < 0.05), while the serum creatinine (Scr) of the AKI group was dramatically higher than that of the non-AKI group (P< 0.001). Compared with the non-AKI group, the loading dose and daily dose of polymyxin B in the AKI group were obviously higher (P< 0.05). The proportion of polymyxin + carbapenems in the AKI group was significantly elevated compared with that in the non-AKI group (P<0.05). The 28-d mortality in the AKI group was significantly higher than that in the non-AKI group (P<0.05). Multivariate logistic regression analysis indicated that cardiopulmonary resuscitation (CPR) history and baseline Scr ≥60 µmol/L before polymyxin B administration were independent risk factors for AKI (P<0.05). Fifty-nine patients met the criteria for AKI recovery analysis from the AKI group. There were 27 cases of unrecovered AKI (45.8%) and 32 cases of recovered AKI (54.2%). Multivariate logistic regression analysis identified male sex as an independent predictor for unrecovered AKI in patients with polymyxin B treatment. Conclusions: Polymyxin B-associated AKI occurs frequently in patients with severe gram-negative bacterial infection, and some patients cannot recover within one week after discontinuation of polymyxin B. Scr≥60 µmol/L before medication was found to be the only independent risk factor for polymyxin B-associated AKI, and it was more difficult for male patients to recover from AKI.