Association between RDW and in-hospital mortality among multiple myeloma patients: a retrospective investigation of the MIMIC-IV database

Red cell distribution width (RDW) has been acknowledged for its prognostic importance in multiple myeloma (MM) patients. However, the connection between RDW and mortality rates among MM patients who are admitted to the Intensive Care Unit (ICU) is still not clear. The aim of this study was to investigate the relationship between RDW and in-hospital mortality among MM patients in the ICU. The retrospective cohort study was carried out with the utilization of the MIMIC-IV database. The study subjects were multiple myeloma (MM) patients who were admitted to the hospital and the intensive care unit (ICU) for the first time. RDW was assessed using the worst values of parameters after admission to the ICU. The main result was in-hospital mortality from all causes. Multivariable-adjusted Cox regression analysis and curve fitting were employed to evaluate the relationship between RDW and in-hospital mortality among patients with multiple myeloma in the ICU. Multivariable Cox proportional hazards regression identified a significant independent association between elevated RDW and increased in-hospital mortality risk (adjusted HR 1.22, 95% CI 1.10–1.35; <i>P</i> &lt; 0.001). Furthermore, after adjusting for all confounding variables, curve fitting revealed a linear relationship between RDW and in-hospital mortality (P for non-linearity = 0.594), indicating a positive correlation between RDW and in-hospital mortality. RDW acts as an independent predictive factor for in-hospital mortality in patients diagnosed with multiple myeloma (MM), and should draw the attention of ICU physicians.