Nursing Care and Functional Health
Functional Health Model,Weakness of Models,Health Indicators, Biomarkers, Psychosocial Factors.
What is Functional Health
Functional
health is a requirement for independent living and is the ability to engage in
daily activities related to personal care and socially defined roles.
Performance of these activities is integral to quality of life and to living
independently and safely. Although functional health represents well being,
most nomenclature reflects deficits in this health.
Terms include disability (
Nagi , 1991), frailty (Lawton, 1991), functional limitation (Johnson, RJ, &
Wolinsky , 1993), and handicap (World Health Organization). Often these terms
are used to refer to other concepts that lead to confusion in nomenclature and
theoretical definitions.
Functional Health Model
The World Health Organization definition of disability
lacks conceptual clarity and theoretical consistency, and this makes
operationalization and establishing relationships difficult.
In the disablement
model (Johnson & Wolinsky ), functional limitations are sometimes confused
with factors affecting these limitations, and perceived health is used as a
proxy for functional limitations. Leidy (1994) proposed nomenclature and
definitions of functional status and other concepts related to this status that
add to the conceptual confusion in this area.
In spite of the confusion related
to nomenclature, Nagi’s (1991) model of disability has been supported by
extensive research and is useful to guide research, because disability in this
model is conceptually clear, logically consistent, and useful in interpreting
current and past research.
Disability (poor functional health) is the result of
a sequence of factors with temporal relationships. Pathology or lifestyle
contributes to functional impairments that are anatomic, physiological, and
psychological abnormalities causing functional limitations at the level of the
whole person (eg, poor memory or inability to get up from a chair).
Functional
limitations then lead to disability, which is the inability to perform daily
tasks or roles independently. Risk factors and external and internal factors
were added to this model to increase its explanatory capacity (Pope &
Tarlov , 1991; Verbrugge & Jette , 1994).
Another significant addition to
Nagi’s model was the notion that upperextremity limitations were more related
to personal care activities of daily living, while lower extremity limitations
were more relevant to instrumental activities of daily living (eg, shopping,
housework, meal preparation) ( Verbrugge & Jette ).
Unique to Nagi’s model
is the notion of thresholds, where a certain amount of change must occur before
change in a subsequent concept is observed. For example, impairments in
mobility arose when the strength of leg muscles was below a certain threshold (
Rantanen et al., 1999; Rantanen et al., 2001).
Weakness of Models
Lacking
in these models is the influence of decision making on disability. Persons
engage in activities that they believe they have the ability to do without risk
of injury or excessive exertion.
Evaluative judgments about the environment and
personal competencies affect decisions about what activities to participate in
and how. Although the congruence between actual and perceived physical
competencies is modest at best, little is known about how these affect
disabilities (Roberts, BL, 1999).
Since
functional health is the ability to engage in everyday activities, a plethora
of research has focused on daily activities related to personal care (ADLs) and
tasks related to providing food and shelter and caring for the home (IADLs),
because impairment in these contribute to excessive dependency, morbidity,
mortality, and poor quality of life.
Health care costs and personal and social
resources needed to manage disability are substantial, particularly as the
baby-boom generation enters older adulthood when the proportion and number of
older adults are expected to increase greatly as well as the associated
financial, personal, and societal costs .
In
2000, 41.9% of elders had at least one disability with nearly 60% of them being
women (Waldrop & Stern, 2003). While only 9.5% had self-care deficits,
20.4% had difficulty going outside, and women were more disabled in this
activity than men (23.0% and 16.8%, respectively).
Racial and ethnic
differences exist, with only 40.4% of non-Hispanic whites being disabled
compared to $2.8% of African Americans. In 1997, 38% of older adults reported severe
disability with 14% and 22% requiring assistance with ADLs and IADLs,
respectively (Administration on Aging, 2003). In the last year of life,
dependency increases ( Covinsky , Eng , Lui, Sands, & Yaffe , 2003; Lunney
, Lynn, Foley, Lipson, & Guralnik , 2003).
ADLs
are hierarchically structured by the complexity of the motor skills required
(Spector, Katz, Murphy, & Fulton, 1987), IADLs are dependent on some of the
same motor skills as ADLs but are more dependent on cognitive capabilities.
ADLs and IADLs are highly related and may represent a continuum of the same
construct (Johnson & Wolinsky , 1993; Thomas, VS, & Hageman, 2003).
Health Indicators
Early
empirical indicators were self-report, whose accuracy cannot be verified and
can be biased by cognitive impairment, social desirability, or minimization of
dependency. Although observational measures reflect what a person is able to
do, they may not reflect what a person actually does.
Gait, dynamic and static
postural stability, and muscle strength are physical factors affecting ADLs and
IADLs ( Guralnik et al., 2000; Roberts , L., 1999), Upper-body function (eg..
muscle strength and range of motion of theorems) was related to ADLs, while
lower-body function (eg, muscle strength of the legs) were associated with
IADLS (Lawrence & Jette , 1996).
Although the effects of exercise on
strength, balance, and mobility are well established, exercise has had little
to no effects on ADLs or IADLS (Latham, Bennett, Stretton, & Anderson,
2004).
Biomarkers
Recently,
biomarkers of increasing dependency associated with frailty have emerged.
Biomarkers of catabolic protein metabolism, pro-inflammatory cytokines, and
other hormones were related to dependency, frailty, and loss of muscle mass and
strength ( Chevalier , Gougeon , Nayar , & Morais , 2003; Ferrucci et al.,
2002 ; Roubenoff , 2003). An understanding of their roles may lead to new
assessment strategies and interventions.
Psychosocial Factors
Relevant
psychological factors include cognitive impairment and depression. Certain
types of social support are factors that can contribute to dependency in daily
activities (Seeman, Bruce, & McAvay , 1996), while men and women use
different types of social support in response to limitations in ADLs and IADLS
(Roberts, BL, Anthony , Matejc zyk , & Moore, 1994).
The role of the
environment has not been well established, except for the increase in
dependency noted during hospitalization and long-term residence in a nursing
home.
Although there is evidence beginning that the relationship between actual
abilities and perceptions of them is low, how these perceptions influence
decisions people make about what activities to perform and how have not been
well studied.
More
research is needed to identify thresh olds in factors related to functional
health where declines in this health occur, and to identify factors and
processes by which people make decisions about performing daily activities.
This knowledge may provide directions for assessment in populations at risk of
poor functional health and may lead to more sensitive assessment strategies.
A
greater understanding of the interplay between environmental and personal
factors with functional health may lead to multidimensional interventions that
may be more effective than the one-dimensional interventions most often
studied.