Association between vitamin B12 levels and mortality in hospitalized older adults.

OBJECTIVES: To investigate the effect of various medications on vitamin B12 status and the association between vitamin B12 levels and mortality. DESIGN: Retrospective cross-sectional study. SETTING: Four internal medicine departments and the geriatrics department at Kaplan Medical Center (KMC), Rehovot and Harzfeld Geriatrics Hospital, Gedera, Israel. PARTICIPANTS: One thousand five hundred seventy patients aged 65 and older hospitalized at the KMC and Hartzfeld Hospital in 2007. MEASUREMENTS: Blood vitamin B12 levels and demographic, clinical, and laboratory data obtained from electronic medical records. RESULTS: Vitamin B12 deficiency (or=350 pmol/L), 68.2% of whom were aged 80 and older. Metformin use was clearly associated with lower vitamin B12 levels. In patients aged 65 and older, an inverse correlation was found between vitamin B12 levels and albumin, metformin, and angiotensin-converting enzyme (ACE) inhibitor use. Age, number of medications, and mortality were linearly correlated with vitamin B12 levels. CONCLUSION: Higher vitamin B12 levels were associated with greater mortality, but it is unclear whether vitamin B12 is a marker or a surrogate marker or even a substance that directly causes death. Further investigation is needed to clarify.