BUN and mortality in patients with heparin-induced thrombocytopenia: A retrospective cohort study

Introduction Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin treatment, characterized by low platelet counts and heightened thrombotic risk. Blood urea nitrogen (BUN), which serves as an indicator of both renal function and illness severity, has been associated with poor outcomes in different contexts. However, its association with mortality in HIT remains poorly understood. Our study aimed to explore this relationship in critically ill patients with HIT. Methods This study was a retrospective cohort analysis utilizing the MIMIC-IV 3.1 database from 2008 to 2019. Patients with HIT were pinpointed through ICD codes. Those without BUN data or whose intensive care unit (ICU) admission was not their first were excluded. The main outcome measured was all-cause mortality, evaluated at multiple time points. The associations were examined using multivariate Cox regression models and Kaplan–Meier survival analysis. Results The research encompassed 246 individuals with HIT (average age 66.2 years, 54.9% male). BUN levels showed a significant association with all-cause mortality during the hospital stay (HR 1.01, 95% CI 1.01–1.02, p = 0.001), within 30 days (HR 1.01, 95% CI 1.01–1.02, p < 0.001), within 90 days (HR 1.01, 95% CI 1.01–1.02, p < 0.001), and within 365 days (HR 1.01, 95% CI 1.01–1.02, p < 0.001). Quartile analysis revealed that the highest BUN quartile (Q4) was associated with the greatest mortality risk compared to the lowest quartile (Q1) at all time points. Kaplan–Meier and restricted cubic spline analyses corroborated these results, indicating a linear relationship between BUN and mortality. Conclusion Elevated BUN levels were significantly associated with higher mortality rates among HIT patients in the ICU. Monitoring BUN levels may help identify patients at greater risk and inform clinical choices. Further research is warranted to elucidate the underlying mechanisms and possible treatments.