No association between subnormal serum vitamin B12 and anemia in older nursing home patients

Since evidence of an association between vitamin B12 (B12) deficiency and anemia in older people is limited and inconclusive, we wanted to investigate this association in old, frail nursing home patients.

The study includes patients admitted to short-term, post-acute care (n = 765) and residents in long-term care (LTC) (n = 1665), in the municipality of Bergen. Anemia was defined according to the WHO criteria: Hb < 13 g/dL in men and < 12 g/dL in women, and as Hb < 11 g/dL, in both sex (moderate/severe anemia). The presence of anemia was analyzed in patients with subnormal (< 250 pmol/L), normal (250-650 pmol/L) and high (> 650 pmol/L) B12, and the association between anemia and clinical parameters, and including B12, was analyzed using logistic regression models. The use of B12 supplementation was investigated in the LTC patients.

Mean age of the 2430 patients was 86 ± 7 years. WHO-defined anemia was seen in 1023 (42%), and moderate/severe anemia in 384 (16%) of the patients. In multiple logistic regression analyses, we found no statistically significant associations of subnormal B12 with WHO-defined anemia or moderate/severe anemia. Renal insufficiency, iron deficiency and CRP > 10 mg/L were significantly associated with both types of anemia, (p < 0.001). Among the LTC residents, 405 (24%) received B12 supplements, 112 (7%) of them had elevated B12 > 650 pmol/L.

In older nursing home patients, no association was observed between subnormal B12 and anemia. Older patients in Western societies with mild/moderate anemia should not be treated with B12 supplements without further investigation.