Red blood cell distribution width-to-monocyte ratio for predicting 90-day mortality of COVID-19 in patients with chronic kidney disease during the Omicron period: a prospective single-center study

We aimed to test whether red blood cell distribution width (RDW) to monocyte percentage ratio (RMR) was associated with the acute-phase prognosis of coronavirus disease 2019 (COVID-19) in chronic kidney disease (CKD) patients. Prospective enrollment and 90-day follow-up of CKD patients with COVID-19 were conducted from December 1, 2022 to January 31, 2023. Demographics, clinical data, and laboratory and radiographic findings were collected, and multiple logistic regression, subgroup analysis, and receiver operating characteristic (ROC) curve analysis were performed. A total of 218 patients were enrolled, with a mean age of 59 years and 69.7% being male. The 90-day mortality rate was 24.8%. The lnRMR level was 5.18 (4.91-5.43) and emerged as an independent risk factor (OR: 3.01, 95% CI: 1.72-5.85). The lnRMR-mortality association was consistent across sex, age, CKD stage, COVID-19 vaccination, and comorbidity subgroups. The area under the ROC curve of lnRMR was 0.737 (95% CI: 0.655-0.819). Our findings indicate that lnRMR is a simple and practical predictor for identifying high-risk CKD patients during the acute phase of COVID-19.