2.1. Participants
All eligible residents in 26 nursing homes in four Norwegian
counties were asked to participate. Nursing homes were selected
in order to reflect the distribution of the entire nursing home
population in the four counties (Selbaek et al., 2008). A minimum
stay of 14 days was required for inclusion in the study. A total of
1165 patients were eligible, of which two were not willing to
participate and five were excluded due to age o50 years, leaving
1158 patients in the study. The mean length of nursing home stay
at the baseline assessment (T0) was 941 (SD¼1014) days. The
residents were then assessed after 12 (T1), 31 (T2), 53 (T3) and 74
months (T4) (see Fig. 1 for attrition from T0 to T4). The mean
follow-up times were: 354 days (SD¼15) from T0 to T1; 934 days
(SD¼34) from T0 to T2; 1580 days (SD¼42) from T0 to T3; and 2232
(SD¼79) days from T0 to T4.