Mean corpuscular volume as a prognostic factor for 30-day mortality in major trauma patients: A retrospective cohort study

Background: Mean corpuscular volume (MCV) is useful for the classification of anemia and has recently been suggested as a prognostic factor for several medical conditions. We investigated the clinical implications of MCV in patients with major trauma. Methods We performed a single-center retrospective review of 2021 trauma patients admitted to the intensive care unit between January 2016 and June 2020. We included 1218 patients aged ≥ 18 years with an injury severity score ≥ 16 in the final analysis. The clinical and laboratory variables were compared between macrocytic (defined as MCV ≥ 100 fL) and normocytic anemia groups. Cox regression analysis was performed to calculate the hazard ratios (HRs) of variables for 30-day mortality, with adjustment for other potential confounding factors. Results The initial mean value of MCV was 102.7 fL in the macrocytosis group (n = 199) and 93.7 fL in the normocytosis group (n = 1019). The macrocytosis group showed a significantly higher proportion of initial hypotension, transfusion within 4 and 24 h, and 30-day mortality than the normocytosis group. Age ≥ 65 years), hypotension (systolic blood pressure ≤ 90 mmHg), transfusion (within 4 hours), anemia (Hb <12 g/d in men, <13 g/d in women), and macrocytosis were significantly associated with 30-day mortality (adjusted HR = 1.4; 95% confidence interval = 1.01 – 1.94; p  = 0.046) in major trauma patients. Conclusion Initial macrocytosis independently predicted 30-day mortality in patients with major trauma at a Level I trauma center. Further studies are required to confirm that increased MCV reflects enlarged erythrocytes.