Associations between the creatinine/cystatin C ratio and 28-day mortality in critically ill patients with sepsis: a retrospective cohort study.

Background: The creatinine/cystatin C ratio (Cr/CysC ratio) has been correlated with muscle mass and survival in several patient populations. However, its relationship with sepsis prognosis remains underexplored. This study investigated the association between the Cr/CysC ratio and 28-day mortality in critically ill patients with sepsis. Methods: In this retrospective cohort study, we analyzed single-center clinical data from a tertiary general hospital in China to investigate 28-day mortality among patients with sepsis. We employed Cox proportional hazards models, Kaplan-Meier survival curves, and restricted cubic spline regression to evaluate the association between the creatinine-to-cystatin C (Cr/CysC) ratio and 28-day mortality. Additionally, subgroup and comprehensive sensitivity analyses were conducted to verify the robustness of our findings. Results: In total, 1,103 patients with sepsis were included, 46.3% of whom were male; moreover, the 28-day mortality rate was 29.9%. After adjustments for potential confounders, an independent relationship was observed between the Cr/CysC ratio and 28-day mortality via multivariable Cox regression analysis (HR: 0.39; 95% CI: 0.24-0.63; Conclusion: In critically ill patients with sepsis, the Cr/CysC ratio on ICU admission was significantly associated with 28-day mortality. However, further validation in larger prospective studies is needed.