1. School of Public Health, Universit� de Montr�al, 7101, Parc avenue C.P. 6128 Succ. Centre-Ville, Montreal, Quebec H3C 3J7, Canada
2. Centre de recherche, Institut universitaire de g�riatrie de Montr�al, 4545, Queen Mary road, Montreal, Quebec H3W 1W4, Canada
3. School of Rehabilitation, Faculty of Medicine, Universit� de Montr�al, 7077, Parc avenue, C.P. 6128 Succ. Centre-Ville, Montreal, Quebec H3C 3J7, Canada
4. Faculty of Nursing Sciences, Universit� de Montr�al, 2375, chemin de la C�te-Ste-Catherine, C.P. 6128 Succ. Centre-Ville, Montreal, Quebec H3C 3J7, Canada
5. Universit� de Montr�al Public Health Research Institute, 7101, Parc avenue C.P. 6128 Succ. Centre-Ville, Montreal, Quebec H3C 3J7, Canada