4.
Functioning and disability in the daily life
One
essential question in the field of functioning in the daily life is how to
better distinguish the origin of the disablement process, whether it is always
linked to life styles, aging or to specific pathological process. The
subsidiary issue is to determine what are the ”disability-risk factors”,
which differ probably from the “disease-risk factors”. Another important
aspect is to evaluate the impact of disability on longevity.
A 32-year prospective study on disability incidence followed two groups of alumni, according to their life habits. The cumulative disability was postponed by 10 years in the low risk group (those who practiced regular physical exercises, had a normal body mass index and did not smoke) in comparison with the high risk group (those who did not exercise, were over weighted and smoked) (45). These data were severely discussed when published (46) and confirmed by another prospective study concerning older participants and taking into account the same associations of risk factors. The risk factor free group showed an average disability score near zero, 10-12 years before death, rising slowly over time, without evidence of accelerated functional decline. In contrast, those with two or more risk factors sustained a greater level of disability throughout the 10-12 years of follow-up and furthermore experienced an increase in their rate of decline 1.5 years prior to death (47).
A
prospective Canadian study tried to identify the exact causes of disability in
older community dwelling persons. It showed that 1) functional disabilities
were twice more frequent above 85 years of age than in the younger studied
population 2) Increasing age was the only significant explanatory variable for
moderate, severe or total disability in the 85+ group - involving difficulties
in walking, showering, shopping, getting to places out of walking distance and
preparing meals 3) On the other hand, diseases were the most significant
explanatory variable associated with functional disabilities in the 65-84 age
group (48). These results need to be confirmed because they are not in
agreement with the majority of the other published survey findings. A
systematic literature review of longitudinal studies published between 1985
and 1997 and dealing with the identification of the “disability-risk
factors” did not mention age itself but in alphabetical order: cognitive
impairment (dementia), disease burden (co-morbidity such as diabetes, heart
failure), increased and decreased body mass index (malnutrition and
overweight), lower extremity functional limitation (osteo-arthrosis, hip
fracture), low frequency of social contacts (loneliness), low level of
physical activity (no regular physical exercise), alcohol abuse compared to
moderate use, poor self-perceived health, smoking and vision impairment (49).
Whatever the role of extreme age or malnutrition (50, 51) or disuse
(52), the whole debate proves once again that one of the main
characteristic of geriatrics is not only to consider the disease but also the
functional impact of diseases on the person.
Moreover, abilities of performing basic and instrumental activities of daily living (ADL and IADL) are linked to the mortality risk. The 5-year follow-up of the 1986 National Health Interview Survey (5’320 community-dwelling individuals, aged 65 and over, self respondents to the ADL-IADL questionnaire) showed that the relative hazard of dying (results adjusted for age, BMI, self rated health status) reached 1.4 in men and 2.5 in women with poor ADL and IADL scores (53). A 4-year study of survival of very old patients hospitalised (n = 446, m.a. # 85 y.o.) in the geriatric department in Geneva confirmed the important relationship existing between functioning and survival. The rate of death 4-year after hospital discharge reached 58.5 %. A multivariate Cox regression model including number of diagnoses, age, gender, living arrangements before hospital admission and number of Functional Instrument Measures (FIM) - items for which help is needed - showed that for each medical diagnosis the risk of dying increased by 8 % but also that for each additional FIM-item, the risk of dying increased by 25 % and when the FIM-cognitive function (problem solving) was involved, the risk increased by 69 % (54).
In
this context, the newest WHO classification of functioning, disability and
health (55) is very useful, by giving to geriatricians a framework to practice
a global geriatric assessment, not limited to physical functioning, but also
including nutritional evaluation, cognitive testing as well as questions about
the human surroundings and technical environment of life. The most important
impact of this WHO classification of functional abilities is the recognition
of the importance of the interactions between health, functioning and
social/technical environment at any age of life. Such a large and
comprehensive assessment is the best way to provide the adequate geriatric
preventive measures or care, whatever the living place of the oldest elderly.