The dynamics and the order of functional loss among nonagenarians: A four-year follow-up study

Abstract

More people worldwide are living into the age of 85 and greater, often referred to as the oldest old. Disability is known to be prevalent in the oldest old. However, the substantial growth of this very old population has not been accompanied with exhaustive follow-up on their functioning status. This study aims to examine changes in the ability to perform daily living (ADL) and mobility activities, as well as the order of functional loss among the 90+ individuals. The data come from two mailed-surveys of the Vitality 90+ Study conducted in 2014 (n= 1637, response rate 80%) and 2018 (n= 1878, response rate 77%). Subjects included in this study have participated in both survey years (n = 499). The study includes two ADLs (bed transferring and dressing) and three mobility activities (moving indoors, walking 400 meters, and using stairs). Changes in the ability to perform ADL and mobility activities between 2014 and 2018 are assessed in three outcomes: disability score, number of disabilities, and degree of severity in individual activities. The association between age, gender, level of education with each of the three outcomes are examined using multinomial logistic regression. The hierarchy of functional loss is established by ranking the activities from the highest to the lowest proportion of deterioration during the study period. In terms of disability score, functioning declines in the 90+ population between 2014 and 2018. As to the number of disabilities, the nonagenarians are divided into two majorities, consisting of those who do not change and those who increase. From 2014 to 2018, the degree of severity increases for walking 400 meters and using stairs while for other activities, it stays the same as in 2014. Older age and being women are statistically significantly associated with poorer functioning in all disability outcomes. In descending order, the largest proportion of deterioration in functioning is found in using stairs, walking 400 meters, moving indoors, dressing, and bed transferring. In conclusion, disability increases over time, and the increase is higher among people with older age and women. However, some stabilities and improvements also exist, suggesting a heterogeneity in functioning in the 90+ population. The order of functional loss found in younger populations seems to remain applicable to the current very old population. This provides an opportunity to establish public health interventions and plan suitable services.