BAR and LAR as mortality predictors in critically ill multiple myeloma patients: a MIMIC-IV study

Validated prognostic tools for critically ill multiple myeloma (MM) patients are lacking. This study evaluated the prognostic value of the blood urea nitrogen to albumin ratio (BAR) and lactate dehydrogenase to albumin ratio (LAR) for mortality in ICU-admitted MM patients using MIMIC-IV. A total of 271 adult MM patients with an index ICU admission were included. BAR and LAR were calculated from laboratory values obtained within 24 hours of ICU entry. Associations with 30-day (primary) and 365-day (secondary) all-cause mortality were assessed using Kaplan-Meier analysis, multivariable Cox regression, restricted cubic spline modeling, and subgroup analyses. After covariate adjustment, each one-unit BAR increase was associated with a 43% higher 30-day mortality hazard (HR 1.43; 95% CI 1.19–1.72; P < 0.001) and a 30% higher 365-day mortality hazard (HR 1.30; 95% CI 1.13–1.49; P < 0.001). For LAR, each one-unit increase conferred 5% (HR 1.05; 95% CI 1.02–1.07; P < 0.001) and 2% (HR 1.02; 95% CI 1.01–1.04; P = 0.004) excess hazards for 30-day and 365-day mortality, respectively. These associations were consistent across most clinical subgroups. BAR and LAR are independently predictive of short- and long-term mortality in ICU-managed MM patients and may serve as accessible bedside risk stratification tools.