AKI in Patients with Multisystem Inflammatory Syndrome in Children

Background: Multisystem inflammatory syndrome in children (MIS-C) is a rare but serious condition associated with COVID-19 with over 9300 cases between May 2020 and January 2023 reported in the US. There are limited published studies on the effects of MIS-C on kidney function in the pediatric population. Etiologies of acute kidney injury (AKI) proposed were cardiac dysfunction, hyperinflammatory state and exposure to nephrotoxins for COVID-19 treatment. However, more large-scale studies are needed to further elucidate the clinical characteristics of kidney injury in children with MIS-C. Methods: We performed a retrospective study of patients between the ages of 0-21 years diagnosed with MIS-C, who were hospitalized at Children’s National Hospital between March 2020 and January 2023. To assess kidney injury, we evaluated serum chemistry, inflammatory markers and urine laboratory values. The Kidney Disease: Improving Global Outcomes (KDIGO) criteria were used to identify 29 patients with AKI and 104 patients without AKI. Results: Among patients with AKI, 79.3% were male and 20.7% were female. Patients with AKI had significantly higher peak CRP levels than non-AKI patients (22.23 vs 16.26 mg/dl, p <0.001). Serum cytokine levels, including TNF-α, IL-1, IL-6, IL-8, and IL-12, were not significantly different between the 2 groups. Patients with AKI had significantly lower levels of albumin at nadir and discharge. A higher proportion of patients with AKI compared to those without AKI were exposed to inotropes (27.6 vs 11.5%,p=0.04), vasopressors (79.3 vs 43.3%,p=0.001) and mechanical ventilation (24.1 vs 3.8%,p=0.002). Urine protein to creatine ratios were similar between AKI and non-AKI patients. Patients with AKI were more likely to have received steroids (55.2 vs 24%,p=0.003) and/or anakinra (93.1 vs 59.6%,p<0.001), than those without AKI. Conclusion: Thedegree of elevation in CRP reflects the hyperinflammatory state in MIS-C patients, which corresponded with AKI development. MIS-C patients who required ventilatory and cardiac support had higher rates of AKI. Receiving steroids and/or anakinra reflects the severity of illness in patients with AKI. This is the largest single center study, to our knowledge, of features and risk factors for AKI in children with MIS-C.