The impact of weight loss and low BMI on mortality of nursing home residents – Results from the nutritionDay in nursing homes

Abstract

Weight loss and low body-mass-index (BMI) are well-known risk factors for mortality among older persons. Both items represent a reduced nutritional state but their nature is different. It is, however, unclear which of these factors is more important for prognosis and if there is interference or interaction between them. To measure the prevalence of low BMI and weight loss in nursing home residents and to analyze their impact on mortality. The nutritionDay in nursing homes is an international annual one-day cross sectional survey evaluating malnutrition and 6-months mortality. The data collected from 2007 to 2012 were analyzed. The mortality risk due to a BMI <20kg/m(2) and weight loss >5kg was calculated by logistic regression analysis with adjustment for confounding factors. In total, 10,298 residents with a mean age of 85 years (78% female) from 191 nursing homes in 13 countries were included in the analysis. Eighteen percent (17.7%) had a low BMI<20kg/m(2), and 11.3% lost>5kg of body weight in the previous year. Low BMI <20kg/m(2) and weight loss >5kg were both independent and significant risk factors for 6-months mortality (OR 1.7 and 1.5; p<0.001 in the adjusted model). In comparison to the effect size of low BMI and weight loss alone, the interaction of both factors was substantial (OR=1.4; p=0.056). The average 6-months mortality was 13.8%. Subjects with BMI ≥20kg/m(2) without weight loss >5kg presented the lowest mortality of 11.2%. In subjects with one of the two features, weight loss >5kg or low BMI <20kg/m(2), mortality was significantly increased to 17.4% and 19.8%, respectively. However, if both features were present simultaneously the mortality increased disproportionally to 35.7% (OR 3.5; p<0.001). In addition, this study presents an overlap and a strong dose-effect relationship of both items with regard to the 6-month mortality. A BMI <20kg/m(2) and weight loss >5kg in one year are both independent and equally relevant risk factors for the 6-months mortality of nursing home residents aged 65 years or older. For this reason weight loss should be avoided and residents with a low BMI and weight loss should receive particular attention and nutritional care.