Prevalence, associated factors, and impact of vitamin B12 deficiency in older medical inpatients.

Purpose: This retrospective cohort study aims to explore the prevalence of vitamin B12 deficiency in older hospitalized adults and identify key factors associated with this deficiency, as well as its impact on frailty and functional decline.

Methods: Data were collected from older adults (≥65 years) sequentially admitted to the Internal Medicine Department of a tertiary university hospital. Clinical and laboratory characteristics, including age, sex, somatometric data, cause of admission, past medical history, chronic medication use, and laboratory tests, were recorded. Frailty and functional status were assessed using the Fried Frailty Scale (FFS), Clinical Frailty Scale (CFS), Barthel Index, and Katz Index. Vitamin B12 levels on admission were categorised as deficient (<200 pg/ml), borderline (200-300 pg/ml), normal (300-999 pg/ml), and high (≥1000 pg/ml).

Results: A total of 894 patients were included. The median age was 83 years and 487 (54.5%) were females. The prevalence of vitamin B12 deficiency was found in 9.1%, while 17.3% of the sample had borderline levels. Multivariate analysis identified polypharmacy (≥5 drugs), low albumin levels/Geriatric Nutritional Risk Index (GNRI), and nursing home residency as independent factors associated with low B12 levels. Multivariate analyses showed that B12 deficiency was significantly associated with higher frailty rates and lower functional status.

Conclusion: Vitamin B12 deficiency is prevalent among hospitalized older patients and is significantly associated with increased frailty and reduced functional status. These findings underscore the importance of routine screening for B12 deficiency in this vulnerable population to improve clinical outcomes and quality of life.