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SF-36
One
of the most widely used measures of health-related quality of
life is the SF-36 and it has a 2-item pain scale. These two items
are shown in Figure 5.1 below.
| Figure
5.1: Two Items From the Pain Scale of the SF-36
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One
SF-36 item measures pain severity, although its wording may capture
both pain severity and frequency depending how the patient interprets
the phrase, "How much …". The second item measures
pain "interference" or disability. Thus, the 2-item
pain scale of the SF-36 is a simple example of a scale capturing
two dimensions of a single symptom -- pain.
PHQ-15
Another unidimensional
scale that has a subject rate 15 common physical symptoms is the
15-item somatic symptom scale of the Patient Health Questionnaire,
or PHQ-15 (Kroenke
et al., 2002).
For example,
the patient is asked on the PHQ-15, "During the past 4 weeks,
how much have you been bothered by abdominal pain?", with
the response options being "not bothered at all," "bothered
a little," and "bothered a lot."
Bother is
a global estimate that may incorporate elements of severity, frequency,
and impairment, depending upon the patient's interpretation of
the term. Thus rating bother is an effort to capture, in a single
question, a "gestalt" in terms of the burden a particular
symptom has imposed upon the subject.
Some symptom
rating scales are multi-dimensional in that they ask separate
questions about each symptom, with each question trying to quantify
one dimension of the symptom.
Memorial Symptom Assessment Scale
An example
of a longer scale capturing 3 dimensions of multiple symptoms
is the Memorial Symptom Assessment Scale (Portenoy
et al.,1994a). The 3 dimensions of symptom burden (temporal
factors, severity, and impairment) are illustrated in Figure 5.2
below, and described in more detail in Section
4: Dimensions of Symptoms (Kroenke,
2001).
| Figure
5.2: The 3 Dimensions of Symptom Burden
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