Functionality and mortality in obese nursing home residents: an example of 'risk factor paradox'?

BACKGROUND: Although the percentage of obese nursing home residents is increasing, few longitudinal studies have reported on functionality and mortality in this subpopulation. The aim of the present study was to explore functionality and mortality in obese nursing home residents during a 1-year follow-up and to compare these results with those of residents within the normal and low BMI range. METHODS: Two hundred residents (147 female, 53 male, mean age 85.6 +/- 7.8 years) from 2 Nuremberg nursing homes were included. Body weight and height were measured in all participants. BMI was calculated and categorized as low (<20 kg/m(2)), normal (20-30 kg/m(2)), and high (>30 kg/m(2)). Handgrip strength, timed "up and go" test, and Barthel's Activities of Daily Living were applied as functional parameters. All measurements were done at baseline and after a 1-year follow-up. RESULTS: At baseline, the prevalence of obesity was 23.5%, whereas low BMI values were present in 8.5% of the residents. After 1 year, there was no significant decline of functionality in the obese group, whereas functional parameters deteriorated significantly in study participants with normal BMI. One-year mortality was lowest in the obese (12.8%), with no deaths in residents with BMI of 35 kg/m(2) or higher. Mortality was highest in residents with low BMI (58.8%). CONCLUSION: In nursing home residents, obesity is associated with increased survival and stable functionality. These observations may therefore be regarded as an expression of "risk factor paradox" in this specific population of older individuals.