Body mass index as a predictor of 1 year mortality in geriatric patients

The predictive value of body mass and functional capacity for 1 year mortality was examined retrospectively in 552 consecutive geriatric patients categorized in 14 diagnosis groups.

Data on body mass index (BMI, kg/m(2)) was retrievable from 337 subjects. In 532 patients, Katz indexes of activities of daily life (ADL, A-G; A=independent, G total dependence) were registered. The mean age (+/- SD) was 81 +/- 8 years, two-thirds were women and 75% lived alone. Mortality data was obtained from the Swedish population records.

Thirty-six per cent of the patients had BMI values < or =43% had BMI 21-25 and 21% > 25. Less than 2% were diagnosed as malnourished. The 1 year mortalities of those with BMI < or = 20, BMI 21-25 and BMI > 25 were 48%, 29% and 18% respectively (P< 0.001). Katz ADL index was significantly worse in those with BMI > 20 as compared with those having BMI < or = 20 (Katz D and C (P< 0.01) respectively). Patients with chronic obstructive lung disease displayed the lowest BMI values, i.e. 20 +/- 4. A logistic regression analysis indicated that BMI, gender and Katz ADL index, but not age, diagnosis or marital status, were independent predictors of 1 year mortality.

Depletion may still be an overlooked problem in geriatric patients, in whom low body mass index appears to be independently associated with imminent death.