B vitamin status, dietary intake and length of stay in a sample of elderly rehabilitation patients

To investigate the relationships between previous diet, biomarkers of selected B vitamins, nutritional status and length of stay. Cross sectional study. Setting: Geriatric rehabilitation patients, Sydney, Australia. Fifty two consenting patients with normal serum creatinine levels and no dementia. Serum vitamin B12, plasma vitamin B6, serum and erythrocyte folate, homocysteine and methylmalonic acid (MMA) concentrations; dietary intake using a validated semi-quantitative food frequency questionnaire and nutritional assessment using the Mini Nutritional Assessment (MNA). Length of stay data were collected from medical records after discharge. The age was 80 +/- 8 year (mean +/- SD), BMI 26.4 +/- 6.8 kg/m(2) and MNA score 22 +/- 3 indicating some risk of malnutrition. Deficiencies of vitamins B6, B12 and folate were found in 30, 22 and 5 subjects respectively. Length of stay was positively correlated with age and MMA (Spearman's correlation 0.4, p < 0.01 and 0.28, p < 0.05 respectively) and negatively correlated with albumin, vitamin B6 and MNA score (Spearman's correlation -0.35, -0.33 and -0.29, p < 0.05). After adjustment for age and sex, ln vitamin B6 and ln MMA concentrations were significant in predicting ln LOS (p=0.006 and p=0.014 respectively). The study indicates a high risk of vitamin B deficiencies in the elderly and suggests that deficiencies of vitamins B6 and B12 are associated with length of stay. This is concerning as B vitamin status is rarely fully assessed.