Body mass index as a predictor of all-cause mortality in nursing home residents during a 5-year follow-up

Abstract

Background: Body mass index (BMI) is considered a short-term mortality predictor, but a consensus has not been reached on its role and that of other nutritional parameters in predicting long-term mortality in nursing home residents.

Objectives: To correlate BMI, Mini Nutritional Assessment scores, and serum albumin levels with the 5-year mortality rate in institutionalized elderly subjects.

Methods: A total of 181 nursing home residents aged ≥ 70 years were included in a 5-year longitudinal study. Data were collected on all participants' nutritional, health, cognitive, and functional status by means of a comprehensive geriatric assessment. Data on the participants' vital status were obtained 5 years after beginning the study, and a survival analysis was conducted using Kaplan-Meier curves and multivariate Cox proportional hazards models.

Results: The 5-year mortality rate was 63%. The deceased subjects (n = 115) had a lower BMI (24.7 ± 4.6 vs 26.6 ± 5.0 kg/m(2); P = .03) and Mini Nutritional Assessment score (18.6 ± 3.7 vs 20.1 ± 3.6; P = .02) than those still alive. Serum albumin levels did not differ between the two groups. Among the three indicators of nutritional status considered in this study, only BMI ≥ 30 kg/m(2) was significantly associated with a lower mortality risk at 5 years (hazard ratio = 0.432; 95% CI 0.20-0.70; P = .04), the risk for death being greater the lower the BMI class (log-rank test: P < .001).

Conclusions: Our findings suggest that BMI is the best of the three parameters considered as a nutritional predictor of nursing home residents' mortality in the longer term, and indicate that a lower mortality risk coincides with a higher BMI.