| | Many
health status measures have been developed, including:
- Sickness
Impact Profile (SIP) (Bergner,
Bobbitt et al., 1976; Bergner,
Bobbitt et al., 1981);
- Nottingham
Health Profile (Hunt,
McKenna et al., 1981);
- Older
Americans Resources and Services (OARS) Multidimensional Functional
Assessment Questionnaire (Fillenbaum
and Smyer, 1981);
- Barthel
Index (Mahoney and Barthel,
1965);
- Physical
Self-Maintenance Scale (Lawton
and Brody, 1969); and
- Short-Form
36 (SF-36) (Ware, 1993) developed
from the Medical Outcomes Study measures (Stewart
and Ware, 1992) (Ware, 1993)
General health
status measures have been extensively studied in patients with
chronic disease. The SIP showed reliability and strong correlations
with clinical evaluation (Deyo,
Inui et al., 1983; Deyo
and Inui, 1984). A version of the SIP for use in nursing homes
correlates with the Katz Activities of Daily Living (ADL) scale
(Gerety,
Cornell et al., 1994).
In addition
to reliability and validity, health status measures
should show responsiveness to clinically significant changes
(Deyo,
Diehr et al., 1991). In a study of 54 patients undergoing
total hip arthroplasty, four short measures of health status,
including the SF-36, were found to be at least as responsive as
the SIP, an established but lengthy measure (Katz,
Larson et al., 1992).
The SF-36
has been shown to be responsive to change in clinical condition
over time in 1700 outpatients with generally reversible illness
(Garratt,
Ruta et al., 1994) but less responsive than a disease-specific
measure in 175 patients with coronary artery disease (Spertus,
Winder et al., 1994). In a long term care setting, short physical
function measures were less responsive for detecting improvement
than for detecting worsening (Siu,
Ouslander et al., 1993).
The SF-36
in particular has dependable psychometric properties. Developed
from the RAND Health Insurance Experiment and the Medical Outcomes
Study, (McHorney,
Ware et al., 1992; Stewart
and Ware, 1992) the SF-36 is a global measure that assesses
health-related quality of life outcomes in a way that is not age,
disease, or treatment specific.
The SF-36
includes eight health concepts :
- Physical functioning;
- Social functioning;
- Mental health;
- Role limitations due to physical
problems;
- Role limitations due to emotional
problems;
- Vitality (energy and fatigue);
- Pain; and
- General health perceptions.
The physical
function measure was shown to be responsive to intervening illness
in an elderly population who were initially healthy (Wagner,
LaCroix et al., 1993).
Each of the
eight concepts is scored from 0 (worst) to 100 (best). SF-36 scores
can be summarized in two scales, a Physical Component Summary
and a Mental Component Summary, each scored from 0-100.
The developers of the SF-36, however, do not recommend combining
either the eight scores or the two subscales into a single summary
index, because such an index is not interpretable in relation
to an underlying health concept (Ware,
1993).
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