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Finding depression in primary care

Diagnostic features
Search
Results
Comment
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.

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

DSM-IV diagnostic criteria

Suggested questions

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

Diagnostic category

DSM-IV criteria

Duration

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

 

Number of

Likelihood ratio

Instrument

Studies

Patients

Positive

Negative

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
 

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


Centre for Epidemiological Studies chipts.ucla.edu/Assessment_Instument/asmt_dp2.html
Beck Depression Inventory www.uea.ac.uk/~wp316/depression.pdf
Primary care evaluation (PDF by email to Robert Spitzer on RLS8@colombia.edu )
Geriatric Depression Scale www.stanford.edu/~yesavage/GDS.english.long.html
Patient Health Questionnaire www.cmecenter.com/primemtoday/
Zung www.wellbutrin-sr.com/hcp/depression/zung.html

Note that some deep links may not work, and you may have to use just the first part of the Internet address


References:

  1. JJ Williams et al. Is this patient clinically depressed? JAMA 2002 287: 1160-1170
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