Disability in activities of daily living: a multifactorial approach

Abstract

Activities of daily living (ADL), such as bathing and doing groceries are essential for maintaining independence in the community. Previous longitudinal studies have shown that about 20 to 30% of older persons (70 years and older) experience ADL disability. Older persons who are ADL disabled have higher rates of morbidity and mortality, and have a poorer quality of life. Disability is a dynamic process in which older persons both develop disability and recover from a period of disability. The recovery rate after a first episode of disability seems to be high (81% within 12 months), yet having experienced disability is a good predictor of future disability, thus, intervention in an early stage may still prevent sustained disability. Therefore, it is important to identify risk factors in an early stage of the disabling process, that might be targeted in preventive strategies. An impaired physical ability is an important component of disability that tends to occur early in the disabling process, and is characterized by irreversible changes in the sensory-motor performance of a person. Hence, an impaired physical ability may be a suitable target for preventive strategies. In the present thesis, we investigated whether a decreased level of physical function and presence of subclinical atherosclerosis were risk factors for ADL disability. In addition, the role of multiple domains of functioning on the current and future ADL disability status was studied. Leg strength and lower body strength were associated with both an impaired physical ability and ADL disability. In addition, other measures of physical function (i.e. handgrip strength, gait speed, physical activity and lung function) were either a risk factor for an impaired physical ability or for ADL disability. From these findings, we can conclude that leg strength is an important factor to consider in preventive strategies. Overall, markers of atherosclerosis and their change over time, were associated with lower handgrip strength and higher rate of change in physical ability. We did not find a direct effect between atherosclerosis and rate of change in ADL disability, which indicates that monitoring atherosclerosis is not effective to prevent or delay the onset of ADL disability. These findings may suggest that ADL disability is a more a consequence of experienced clinically manifest vascular events, rather than the effect of progression of atherosclerosis. There is not a single domain that is particularly important in determining current ADL status, but multiple health related domains contribute to current ADL disability. This finding stresses the importance of a multifactorial intervention. Focus on a single domain in preventive strategies could lead to a less effective strategy toward the delay or prevention of ADL disability. Using a multifactorial prediction model, including the number of chronic diseases, muscle strength, age, gender and socioeconomic status, we were able to identify individuals who were at high risk of developing ADL disability over a course of ten years. In the development of preventive strategies, we should focus on a multifactorial approach, long duration of the intervention, inclusion of middle-aged persons, and impaired physical ability as important outcome