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The
PHQ-15 overlaps with each of the other symptom screeners, in terms
of symptoms covered as well as any two of the other screeners
overlap with one another. It is shorter in length and focuses
only on current symptoms (which has proven more reliable than
lifetime symptom recall). Its 15 symptoms account for over 90%
of symptom-related visits in medical practice, excluding those
related to upper respiratory infections.
At appropriate
cutpoints the PHQ-15 identifies a similar group of somatizing
patients as the other screeners. It also has been validated as
a continuous measure of somatic symptom severity, with cutpoints
of 5, 10, and 15 representing mild, intermediate, and high levels
of somatization.
The PHQ-15
(and its precursor, the PRIME-MD) have been validated in 7000
outpatients in three large studies, and is increasingly considered
one of the better measures for somatization (Kroenke
et al.,1994; Kroenke
et al.,1997b; Kroenke
et al.,1998; Kroenke
et al., 2002; Simon
et al.,1999).
Since the
PHQ-15 is self-administered, responses cannot separate those symptoms
which are medically unexplained from those that relate to a discrete
medical disorder. While this requires clinical judgment, research
has shown that high total symptom count and severity serve as
a reasonable surrogate for somatization.
Finally, the
PHQ-15, or other multi-symptom measures such as the symptom subscale
of the SCL-90 or Portenoy's multidimensional symptom scale, may
be used as secondary measures in studies where a validated generic
instrument to assess somatic symptom burden is desired.
Medically
unexplained symptoms by themselves do not constitute a psychiatric
diagnosis. When one is unable to identify psychological factors
and link them as probable causative or contributory factors to
the physical symptoms, it is more appropriate to consider the
symptoms as idiopathic rather than diagnose the patient with a
somatoform disorder.
Even when
psychological factors are responsible for somatic symptoms, other
mental disorders such as depression and anxiety are often the
etiology rather than a primary somatoform disorder. This is important
because treatments are better established for depression and anxiety
for somatoform disorders.
An algorithmic
approach to proceeding from an unexplained physical symptom to
a diagnosis of a somatoform disorder is shown in Figure 17.1 below.
| Figure
17.1. DSM-IV Unexplained Physical Symptoms Algorithm
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|---|
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Consider
the role of a general medical condition or substance
use and whether the unexplained symptoms are
better accounted for by another mental disorder.
-
Symptoms due to a general medical condition
- Functional
somatic syndrome †
- Substance-induced
(including medication) symptoms
- Other
mental disorders
† Irritable bowel syndrome, fibromyalgia, temporomandibular
disorder, etc.
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If
the predominant symptom is an unexplained apparently
neurological symptom, consider
-
Conversion Disorder 300.11
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|
If
the predominant symptom is pain, and if the
clinician suspects psychological factors are playing
a role in the onset, severity, or exacerbation of
the pain, consider
|
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If
there is excessive preoccupation with the fear
of having a disease, consider
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If
multiple unexplained physical symptoms are
present, consider
- Undifferentiated
Somatoform Disorder 300.81
- Somatization
Disorder 300.81
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|
If
clinically significant symptoms are present but the
criteria are not met for any of the previously
described disorders, consider
- Somatoform
Disorder Not Otherwise Specified 300.81
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|
If
the clinician has determined that a disorder is not
present but wishes to note the presence of symptoms,
consider
- Unexplained
General Medical Complaint 780.9
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| Adapted
from Diagnostic and Statistical Manual for Mental Disorders,
4th Ed: Primary Care Version |
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