Association between blood urea nitrogen-to-creatinine ratio and mortality in critically ill patients with lung cancer: an analysis from the MIMIC database

Recently, the blood urea nitrogen-to-creatinine ratio (BCR) has been considered a potential indicator of various clinical outcomes. However, the association between this ratio and mortality in critically ill patients with lung cancer remains unclear. This study examined the connection between BCR levels and outcomes in critically ill patients with lung cancer. A retrospective cohort study was conducted using the MIMIC-IV database, with BCR divided into tertiles. The 28-day and 365-day mortality rates were analyzed as the primary outcome measures. The association was assessed using Kaplan–Meier survival analysis and the Cox proportional hazards model. A subgroup analysis was performed to verify the study results. This study included 1,226 critically ill patients with lung cancer. The results of Cox proportional hazards regression analysis showed that each 10-unit increase in BCR significantly increased the risk of death within 28 days (hazard ratio [HR] = 1.23, 95% confidence interval [CI]: 1.13–1.34) and the risk of death within 365 days (HR = 1.19, 95% CI: 1.11–1.27). Consistent results were observed in the subgroup analysis. This investigation suggests that an elevated BCR may be independently associated with an increased risk of mortality in critically ill patients with lung cancer. This study highlights the possibility of using the BCR as a marker for predicting lung cancer outcomes.