Association of country income level with the characteristics and outcomes of critically ill patients hospitalized with acute kidney injury and COVID-19 by Wainstein, M, Spyrison, N, Dai, D, Ghadimi, M, Chávez-Iñiguez, JS, Rizo-Topete, L, Citarella, BW, Merson, L, Pole, JD, Claure-Del Granado, R, Johnson, DW, Shrapnel, S