The mean corpuscular volume (MCV) is a hematological biomarker associated with COVID-19 mortality risk.

AIM: This study aimed to investigate the role of mean corpuscular volume (MCV) as a predictor of mortality due to COVID-19. MATERIALS AND METHODS: This retrospective, single-center, and longitudinal study included 122 patients with COVID-19. RESULTS: Compared to the survivor's group, the non-survivors had higher MCV (92.13 ± 3.67 fL), neutrophil-to-lymphocyte ratio [NLR] (16.99 [21.31]), platelet-to-lymphocyte ratio [PLR] (350.33 [304.68]), and systemic immune-inflammation index [SII] (3684.92 [4073.25]) levels (p < 0.05 for all). The optimal cutoff values for predicting in-hospital COVID-19 mortality, determined by the Youden index, indicated that patients with MCV > 89 fL, NLR > 8.69, PLR > 418.08, or SII > 2149.36 were at a higher risk of death due to SARS-CoV-2 infection. The area under the curves (AUC) of NLR, SII, MCV, and PLR was sufficient for accurate prediction. COVID-19 patients with MCV > 89 fL and PLR > 418.08 were 3.65 (95% CI 1.03-12.87; p = 0.043) and 5.08 (95% CI 1.06-24.22; p = 0.041) times more likely to die than those without these values, respectively. MCV was positively correlated with age, mean corpuscular hemoglobin (MCH), urea, blood urea nitrogen (BUN), and creatinine. CONCLUSION: MCV > 89 fL and PLR > 418.08 at the time of hospital admission were associated with an increased COVID-19 mortality risk.