Relationship of blood urea nitrogen levels with 28-day mortality among critically ill individuals diagnosed with central venous catheter-associated infections

Background Currently, the association of blood urea nitrogen (BUN) levels with 28-day mortality in critically ill patients diagnosed with central venous catheter (CVC)-related infections has not been fully elucidated. This study sought to elucidate the relationship between BUN levels and 28-day mortality in critically ill patients experiencing CVC-associated infections. Methods This investigation, designed as a retrospective cohort analysis, employed data extracted from the Medical Information Mart for Intensive Care (MIMIC) IV database, gathering demographic information, vital signs, laboratory results, and comorbidities for all participants following their intensive care unit (ICU) admission. Multivariate Cox proportional hazards regression models, including subgroup and interaction analyses, were applied to examine the independent association of BUN with 28-day mortality. Results The study enrolled 410 critically ill individuals diagnosed with CVC-related infections. The study cohort had a mean age of 60.6 years, and 55.1% (226/410) of participants were male. The overall 28-day mortality rate was 16.1% (66/410). In unadjusted analyses, elevated BUN levels at admission were significantly correlated with higher 28-day mortality (HR 1.01; 95% CI 1.01–1.02; p  < 0.001), indicating that each 1 mg/dL rise in BUN was associated with a 1% increase in mortality risk. This association persisted after adjusting for potential confounders [(adjusted Hazard Ratio (HR) 1.01; 95% confidence Interval (CI) 1.01–1.02; p  = 0.004). When BUN levels were divided into quartiles, patients in the highest quartile (Q4) exhibited a significantly greater mortality risk compared to those in the lowest quartile (Q1) (adjusted HR 5.44; 95% CI 1.49–19.89; p  = 0.01). Subgroup analyses demonstrated no significant interaction effects (all p -values for interaction > 0.05). Conclusions Higher BUN levels upon admission were independently associated with increased 28-day mortality in critically ill individuals diagnosed with CVC-associated infections. These findings indicate that BUN levels may function as a useful biomarker for evaluating risk.