The Belgian Health Interview Survey (BHIS) data from 1997, 2001, 2004, and 2008 were used in this analysis. The BHIS is a national household survey, repeated every 3–5 years, commissioned by all the ministers responsible for public health at the federal, regional, and community levels in Belgium. It is conducted by the Scientific Institute of Public Health in collaboration with Statistics Belgium [18]. A multistage sampling design with geographical stratification (regions and provinces) and clustering (municipalities and households) was applied to obtain a representative sample of the Belgian population, including elderly individuals living in nursing homes and homes for the elderly. Proxy interviews were mandatory for individuals aged