Association between mean corpuscular hemoglobin concentration and mortality in ICU patients with acute kidney injury:...

The prognostic value of mean corpuscular hemoglobin concentration (MCHC) in ICU patients with acute kidney injury (AKI) is unclear.

We performed a retrospective multicenter cohort study using MIMIC-IV and eICU-CRD. Adults with AKI and an admission MCHC (first 24 h) were included. Outcomes were 30-and 90-day in-hospital mortality. Survival was compared across MCHC quartiles, and Cox models (with restricted cubic splines) estimated adjusted associations.

Among 111,817 patients (MIMIC-IV n = 54,422; eICU-CRD n = 57,395), higher MCHC was associated with lower mortality. Survival differed across MCHC quartiles (log-rank p < 0.0001 in both cohorts). In adjusted models, the highest vs. lowest MCHC quartile had a lower risk of death (MIMIC-IV HR 0.65, 95% CI 0.60-0.70; eICU-CRD HR 0.62, 95% CI 0.58-0.66). Spline analyses suggested a nonlinear association in MIMIC-IV and an approximately linear association in eICU-CRD.

Admission MCHC was associated with 30-and 90-day mortality in ICU patients with AKI across two large databases. MCHC may aid risk stratification in this population.