Elevated baseline vitamin B12 level and all-cause mortality risk in patients with sepsis: a cohort analysis.

Background: Elevated serum vitamin B12 levels have been associated with adverse outcomes in various clinical settings; however, the prognostic significance of pre-existing vitamin B12 elevation measured before sepsis onset remains unclear. This study examined the association between pre-sepsis vitamin B12 levels and clinical outcomes in adults with sepsis. Methods: This retrospective cohort study utilized the TriNetX database to identify adults diagnosed with sepsis between 2010 and 2024. Patients with elevated vitamin B12 levels (≥1,000 pg./mL) measured within 3 months before sepsis diagnosis were compared with those having normal levels (300-900 pg./mL) using 1:1 propensity score matching. The primary outcome was 90-day all-cause mortality. The secondary outcomes included major adverse cardiovascular events, organ failure, intensive care unit (ICU) admission, and progression to severe sepsis. Results: After propensity score matching, 18,830 patients per group (37,660 patients in total) were included in this cohort. Elevated pre-sepsis vitamin B12 levels were associated with increased 90-day mortality [26.3% vs. 21.8%; hazard ratio (HR): 1.29, 95% confidence interval (CI): 1.24-1.35, Conclusion: Elevated pre-sepsis vitamin B12 levels are associated with increased short-term mortality and adverse outcomes in patients with sepsis, suggesting that elevated pre-sepsis vitamin B12 levels may serve as a risk-associated biomarker, although its independent prognostic utility requires further validation.