[Predictors for the onset of different types of homeboundness among community-living older adults: two-year prospective study].

BACKGROUND: Little is known about predictors for the onset of different types of homeboundness among community-living older adults. PURPOSE: This 2-year prospective study examined predictors for the onset of "type 1" and "type2" homeboundness (see definitions below) among community-living older adults. METHODS: Study subjects comprised all residents aged 65 years and over living in Yoita town, Niigata, Japan, who answered the baseline (2000) and follow-up (2002) surveys. Persons were defined as being homebound if he/she went outdoors once a week or less often. Homeboundness was further classified into "type 1" or "type 2", based on the hierarchical mobility level classification (levels 1 or 2 vs. levels 3 or over). "Type 1" homebound persons included those who could not get out into the neighborhood without assistance (i.e., level 3 or over). "Type 2" included those who were homebound, though they could get out at least into the neighborhood unassisted (i.e., level 1 or 2). A stepwise, multiple logistic regression model was used to identify the most parsimonious combination of risk factors for each type of homeboundness. RESULTS: Out of 1,322 persons who were level 1,2 non-homebound at the baseline, 77.6% remained as level 1,2 non-homebound (n = 1,026), but 1.7% were "type 1" homebound (n = 22), and 4.8% were "type 2" homebound (n = 66) at follow-up. The final model for prediction of "type 1" homeboundness at follow-up included: advanced age (OR for 5 year-increment: 2.10; 95%CI: 1.36-3.24), not having a job (OR: 4.42; 95%CI: 1.21-16.2), unable to walk 1 km (OR: 4.24; 95%CI: 1.37-13.1), and a low cognitive function identified as MMSE 5 (OR: 2.18; 95%CI: 1.23-3.88), a low cognitive function (OR: 2.72; 95% CI: 1.47-5.05), not having close friends (OR: 2.30; 95%CI: 1.08-4.87), and not having a walking or calisthetics habit (OR: 2.21; 95%CI: 1.26-3.86). CONCLUSIONS: Reduced physical and mental functioning contribute to the subsequent occurrence of "type 1" homeboundness. Additionally, psychosocial factors are independent predictors of "type 2" homeboundness. These results suggest that different public health strategies might be required for prevention of the different types of homeboundness in Japanese older adults.