Association between hemoglobin and in-hospital mortality in critically ill patients with sepsis: evidence from two large databases

The relationship between baseline hemoglobin levels and in-hospital mortality in septic patients remains unclear. This study aimed to clarify this association in critically ill patients with sepsis.

Patients with sepsis were retrospectively identified from the Medical Information Mart for Intensive Care-IV (MIMIC-IV 2.2) and eICU Collaborative Research Database (eICU-CRD). Multivariate logistic regression analysis and restricted cubic spline regression were used to investigate the association between hemoglobin and the risk of in-hospital mortality. Additionally, a two-part linear regression model was used to determine threshold effects. Stratified analyses were also performed.

A total of 21,946 patients from MIMIC-IV and 15,495 patients from eICU-CRD were included in the study. In-hospital mortality was 14.95% in MIMIC-IV and 17.40% in eICU-CRD. Multivariate logistic regression showed that hemoglobin was significantly and nonlinearly associated with the risk of in-hospital mortality after adjusting for other covariates. Furthermore, we found a nonlinear association between hemoglobin and in-hospital mortality, with mortality plateauing at 10.2 g/dL. The risk of mortality decreased with increasing hemoglobin levels below 10.2 g/dL but increased when hemoglobin levels exceeded 10.2 g/dL. These findings were validated in the eICU-CRD dataset.

A nonlinear correlation between hemoglobin levels and in-hospital mortality was observed in patients with sepsis, with a threshold of 10.2 g/DL. These findings suggested that hemoglobin levels below or above the threshold may be associated with worse outcomes, warranting further investigation in prospective studies.