Finding depression in primary care
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Diagnostic features
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Search
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Results
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Comment
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Websites for common instruments
Depression is awfully common. In primary care, estimates of the prevalence of
major depression range from 5% to 9%, and that's just the patients. We all get
fed up, we all get tired, we all get to feel a bit worthless from time to time.
We may not be well, or be recovering from the last in a succession of viruses.
Sometimes we pull ourselves together, and sometimes we can't. The problem for
primary care professionals is telling major depression from being fed up, and
then whether that depression signifies some unrecognised problem.
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A terrific new systematic review [1] pulls the subject together beautifully, and
gives us a clear insight into the latest diagnostic criteria for depression plus good
information on the performance of various simple screening and diagnostic systems for
primary care.
Diagnostic features
Based on the criteria from Diagnostic and Statistical Manual of Mental Disorders
(DSM-IV), eight symptoms and criteria are defined, together with some suggested
questions for patients (Table 1). Depending on the answers to the questions and the
duration of the symptoms depression can be major or minor, or can just indicate
dysthymia (melancholy, Table 2). Can diagnostic questionnaires be of any help?
Table 1: DSM-IV diagnostic criteria and suggested questions
Symptom
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DSM-IV diagnostic criteria
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Suggested questions
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| Depressed mood |
Depressed mood most of the day, nearly every
day |
How has your mood been lately? How often does this
happen? How long does it last? |
| Anhedonia |
Markedly diminished interest or pleasure in almost
all activities most of the day, nearly every day |
Have you lost interest in your usual activities? Do
you get less pleasure in things you used to enjoy? |
| Sleep disturbance |
Insomnia or hypersomnia nearly every day |
How have you been sleeping? How does that compare
with your normal sleep? |
| Appetite or weight change |
Substantial change in appetite nearly every day or
unintentional weight loss or gain (≥5% of body weight in a month) |
Has there been any change in your appetite or
weight? |
| Decreased energy |
Fatigue or loss of energy nearly every day |
Have you noticed a decrease in your energy
level? |
| Increased or decreased psychomotor
activity |
Psychomotor agitation or retardation nearly every
day |
Have you been feeling fidgety or had problems
sitting still? Have you slowed down, like you were moving in slow motion or stuck
in mud? |
| Decreased concentration |
Diminished ability to think or concentrate, or
indecisiveness, nearly every day |
Have you been having trouble concentrating? Is it
harder to make decisions than before? |
| Guilt or feelings of worthlessness |
Feelings of worthlessness or excessive guilt nearly
every day |
Are you feeling guilty or blaming yourself for
things? How would you describe yourself to someone who had never met you
before? |
| Suicidal ideation |
Recurrent thoughts of death or suicide |
Have you felt that life is not worth living or that
you'd be better off dead? Sometimes when a person feels down or depressed they
might think about dying. Have you been having any thoughts like that? |
Table 2: Diagnostic categories for depression and dysthymia (melancholy),
and criteria for diagnosis
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Diagnostic category
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DSM-IV criteria
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Duration
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| Major depression |
≥5 depressive symptoms, including depressed mood
or anhedonia, causing significant impairment in social, occupational, or other
important areas of functioning |
≥2 weeks |
| Minor depression |
2 to 4 depressive symptoms, including depressed mood
or anhedonia, causing significant impairment in social, occupational, or other
important areas of functioning |
≥2 weeks |
| Dysthymia |
3 or 4 dysthymic symptoms, including depressed mood,
causing significant impairment in social, occupational, or other important areas
of functioning |
≥2 years |
Search
MEDLINE and the Cochrane register of depression trials were searched for
English-language studies evaluating the performance of case-finding instruments
in primary care and the reliability of the clinical interview. Case-finding
instruments had to have easy to average literacy requirements, be scored without
a calculator, have a depression-specific component and be evaluated in at least
one study with at least 100 subjects. Reliability studies had to have diagnoses
made by two or more clinicians reviewing audio- or videotape interviews.
Results
Eleven questionnaires with between one and 30 items were found in 28 studies
involving over 25,000 patients for case-finding. Major selection bias occurred in
nine trials, which were then excluded. Three instruments, Beck depression
inventory, Centre for Epidemiological Studies depressive screen and the Zung
self-assessment depressive scale were developed specifically to identify
depression. None of the instruments took more than five minutes to administer,
and most could be done in two or three minutes.
The results for finding major depression in a primary care setting are shown in
Table 3, with the mean likelihood ratios for a positive and a negative result.
The likelihood ratio for a positive result was about 3 and for a negative result
was about 0.2. In a clinic with an 8% prevalence of major depression of
dysthymia, a clinician seeing 100 patients a week can expect that 30 will screen
positive for depression, of whom seven would meet the criteria for major
depression after a more careful interview. In the 70 patients who screen
negative, one would actually be clinically depressed.
Table 3: Diagnostic utility of case-finding instruments for depression in
primary care
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Number of
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Likelihood ratio
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Instrument
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Studies
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Patients
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Positive
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Negative
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| Centre for Epidemiological Studies
depressive screen |
10 |
3038 |
3.3 |
0.2 |
| Symptom driven diagnostic system |
4 |
1682 |
3.5 |
0.2 |
| Beck depression inventory |
4 |
952 |
4.2 |
0.2 |
| Zung self assessment depression
scale |
4 |
667 |
3.3 |
0.4 |
| Primary care evaluation of mental
disorders |
2 |
967 |
2.7 |
0.1 |
| Hopkins symptom check list |
2 |
946 |
3.2 |
0.2 |
| Geriatric depression scale |
2 |
165 |
3.3 |
0.2 |
| Patient health questionnaire |
1 |
585 |
12 |
0.3 |
| Single question |
1 |
291 |
2.3 |
0.2 |
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In seven studies using a semistructured interview, agreements between examiners
was good, with kappa values generally above 0.7.
Comment
This is a splendid review, with much more useful information than can be
conveyed by précis. For any primary care organisation or professions
wanting to improve the determination of depression in a primary care setting
reading this is an essential start. Links to the various instruments used in the
study (not all of them have a website), are shown in the box below.
Websites for common instruments
Note that some deep links may not work, and you may have to use just the
first part of the Internet address
References:
- JJ Williams et al. Is this patient clinically depressed? JAMA 2002 287:
1160-1170
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