Biomedical Engineering Reference
In-Depth Information
Many different studies have been dedicated to exploring the trends in mortality, morbidity,
and disability. The U.S. Census Bureau (Kinsella and He 2009) reports that the prevalence
of chronic conditions is increasing while disability is decreasing in developed countries,
whereas the prevalence of disability is likely to increase in developing countries.
In the Rotterdam study, an analysis of the incidence of disability and its risk factors in
multiple dimensions in community-dwelling women and men of older age, found that
age, self-rated health, being overweight, depression, joint complaints, and medication use
were predictors of disability for both men and women. Stroke, falling, and the presence of
comorbidities predicted disability in men only, whereas having a partner, poor cognitive
functioning, osteoarthritis, and morning stiffness predicted disability in women (Tas
et al. 2007).
According to the compression morbidity theory, a recent study identified clinically dis-
tinct trajectories of disability in the last year of life and attempted to determine whether
and how the distribution of these trajectories differed according to the condition leading
to death (Gill et al. 2010). The results demonstrated that, for most of the decedents, the
course of disability at the end of life did not follow a predictable pattern on the basis of
the most common conditions leading to death: cancer, advanced dementia, organ failure,
frailty, sudden death, and other conditions. Dementia was the condition with the least
variation and was characterized by high levels of disability throughout the last year of life.
For the other conditions, catastrophic disability was found a few months before death. The
authors commented on evidence supporting the need to provide services at the end of life,
especially for patients with dementia. In line with this, it was shown that dementia is the
most important risk factor for the development of geriatric syndromes during hospitaliza-
tion (Mecocci et al. 2005), suggesting that the hospital environment should be adapted to
the needs of patients with cognitive problems.
Although it has been documented that disabilities and limitations have shown improve-
ments over the last decade (Freedman et al. 2002), and that people are living longer than
they did previously with less disability and fewer functional limitations (Christensen et al.
2009), older people (particularly of the oldest age) are often described as a “frail” group
who are particularly vulnerable to diseases and functional disability and who are at a
greater risk of losing the ability to manage their daily activities independently (Fried et al.
2001; Song et al. 2010).
13.2.3 Frailty
Frailty is defined as “a clinical state of increased vulnerability and decreased ability to
maintain homeostasis that is age-related and centrally characterized by declines in func-
tional reserve across multiple physiologic systems” (Fried et al. 2009, p. 634). A recent
review identified different models of frailty coexisting in the literature where the “physical
phenotype” and the “multidomain phenotype” that can be considered as extreme points
on a continuum ranged from physical aspects to multiple aspects, respectively, including
cognitive, functional, and social domains (Abellan van Kan et al. 2010). The main differ-
ences between the proposed models are due to the differences in considering physical,
functional, cognitive, and social domains as components of the frailty model or as frailty
outcomes. For example, disability is considered by many as a component of frailty and by
others as an outcome; in fact, a survey of 62 geriatricians, focusing on the significance of
the terms “frailty” and “disability,” showed that 98% of the respondents considered frailty
and disability to be two distinct entities with different prognoses and health-care implica-
tions (Fried et al. 2004). A different predictive capacity for clinical outcomes is associated
