[Prognosis of different types of homeboundness among community-living older adults: two-year prospective study]

Abstract

Purpose: This 2-year prospective study was conducted to determine prognosis of two different types of homeboundness among community-living older adults and explore whether those types of homeboundness exert independent effects even after controlling for potential confounders.

Methods: Out of all residents aged 65 years and over who lived in Yoita, Niigata, Japan (n = 1,673), 1,544 persons participated in the baseline survey which was conducted in November, 2000 (response rate, 92.2%). They were followed for the subsequent 2 years in terms of mortality, institutionalization and functional status (mobility, IADL, BADL, and cognition). Persons were defined as being homebound if he/she went outdoors only once a week or less often. Homeboundness was further classified into types 1 or 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., levels 3 or over). Type 2 included those who were homebound though they could get out at least into the neighborhood unassisted (i.e., levels 1 or 2). We compared two-year prognosis between the type 2 homebound cases and controls (the non-homebound individuals in levels 1 or 2), or the type 1 homebound and controls (the non-homebound in levels 3 or over). Multiple regression analysis or multiple logistic regression models were used to analyze independent effects of the homebound status on the prognosis, controlling for potential confounders such as age, gender, chronic conditions, functional status, and psychosocial variables at baseline.

Results: At baseline there were 1,322 non-homebound in levels 1 or 2 (87.0%), 81 type 2 homebound (5.3%), 39 non-homebound in levels 3 or over (2.6%), and 78 type 1 homebound older persons (5.1%) . As compared to controls, type 2 homebound elderly showed increased risks of functional decline even after controlling for potential confounders. Relative risks of type 2 homeboundness for developing mobility loss, IADL and ADL disability, and cognitive impairment (MMSE < 20) were 3.20(95% CI, 1.60-6.38), 2.85(1.20-6.82), 1.52(0.61-3.75), and 3.05(1.06-8.78) in the partially adjusted model, and 2.49(1.20-5.17), 2.25(0.90-5.63), 1.46(0.54-3.94) and 2.41(0.71-8.17) in the fully adjusted model. Type 1 homebound elderly showed an increased risk for mortality (33.3% vs. 5.1%), but a lower risk for institutionalization (9.0% vs. 25.6%). The independent effect of type 1 was not significant when mortality and institutionalization were combined (relative risk, 2.05[0.54-7.75] in the fully adjusted model).

Conclusions: Type 2 homeboundness is an independent risk factor for functional decline among competent older persons, while the prognosis of older persons with a low functional state is poor, regardless of type 1 homeboundness or not.