Psychiatry's main method to prevent mistaken diagnoses of depression doesn't work: NYU study

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http://www.eurekalert.org/pub_releases/2010-02/nyu-pmm022410.php

Psychiatry's main method to prevent mistaken

diagnoses of depression doesn't work: NYU study

Empirical analysis challenges DSM

A study in the March edition of the American Journal of

Psychiatry

senior-authored by Jerome C. Wakefield, a professor at the Silver

School of Social Work at New York University with Mark Schmitz of

Temple University and Judith Baer of Rutgers University, empirically

challenges the effectiveness of psychiatrists' official diagnostic

manual in preventing mistaken, false-positive diagnoses of depression.

The findings concerning the American Psychiatric

Association's Diagnostic and Statistical Manual of Mental Disorders'

(DSM) criteria for diagnosing depression rebuts recent criticism of

earlier research by Wakefield. That earlier research suggested that

misdiagnoses of depression are widespread, and touched off considerable

controversy.

According to the DSM, the diagnosis of major depression

requires the presence – for two weeks – of at least five possible

symptoms out of a list of nine, which include, for example, sadness,

loss of interest in usual activities, lowered appetite, fatigue, and

insomnia. However, these symptoms can also occur in normal responses to

loss and stress. False positive diagnoses occur when someone reacting

with intense normal sadness to life's stresses is misdiagnosed as

having major depressive disorder. Recent studies suggest that a very

large percentage of people have such symptoms for two weeks or longer

at some point in their lives; therefore, how many of these individuals

really are afflicted by a mental disorder or are responding within

normal limits to loss or stress has been a matter of debate.

The

journal article, entitled "Does the DSM-IV Clinical Significance

Criterion for Major Depression Reduce False Positives? Evidence From

the National Comorbidity Survey Replication," examines the primary

method by which the official diagnostic criteria for depression –the

Clinical Significance Criterion (CSC) – are supposed to distinguish

normal from disordered cases and thereby prevent false positive

diagnoses. The CSC was added to the symptom and duration criteria in

the DSM's fourth edition in 1994 (DSM-IV) in the wake of criticism that

too many of the listed symptoms – loss of appetite, say, or sadness,

insomnia, or fatigue – were being identified as evidence of major

depressive disorder even when they were mild and possibly normal

responses to distress arising from such events as the loss of a job,

the dissolution of a marriage, or other triggers for sadness, and that

such errors might be contributing to the very high reported rates of

untreated depression in the American population drawn from

epidemiological surveys. Under the 1994 DSM revision, in addition to

the two weeks of sadness and other depressive symptoms, a specified

minimal "clinically significant" threshold in the form of harm due to

distress or role impairment (in occupational, family, or interpersonal

contexts) must have resulted from the symptoms in evidence before they

could be considered signs of depression. Researchers have subsequently

assumed – without definitive evidence – that the CSC eliminates

substantial numbers of false positives.

In a 1999 article in American Journal of Psychiatry,

Wakefield and co-author Spitzer, the originator of the modern

DSM symptom-based approach to diagnosis, argued that the CSC would not

eliminate false-positive diagnoses of major depression because anyone

having the specified symptoms – even an individual experiencing a

normal intense reaction to loss – would be likely to experience

distress or role impairment. Thus, they asserted, the CSC was redundant

with the symptom criteria and could not distinguish normal from

disordered symptoms—a claim that has come to be known as the

"redundancy hypothesis." The researchers' argument was purely

conceptual, and largely ignored.

The issue of whether the

redundancy hypothesis is correct became suddenly more important after

Wakefield senior-authored a much-discussed 2007 article in Archives of

General Psychiatry. The article argued that there were indeed large

numbers of false-positive diagnoses of major depression in community

surveys of mental disorder—possibly as high as 25% to 33%. However,

that study used data from a national survey that was conducted before

the DSM-IV's addition of the CSC to the major depression diagnostic

criteria. Thus, there was no CSC in the criteria that Wakefield and his

team used to identify cases of major depression at the time. Critics of

that study argued that the lack of a CSC was fatal to the argument

because if the CSC had been used, then the supposed false-positive

diagnoses that Wakefield and his group identified would likely have

been eliminated as cases too mild for diagnosis. For example, one noted

psychiatrist argued that Wakefield's results were due to a "glitch" in

the diagnostic criteria Wakefield used, and that the diagnosed

individuals identified by Wakefield as having normal reactions would

have been eliminated from the depression category if current diagnostic

criteria including the CSC were used. A paper later submitted by

Wakefield that built on the 2007 article was rejected for publication

partly based on a reviewer's assertion that if the CSC had been

included in the earlier study, the supposed false positives likely

would have been eliminated. So, the issue of whether the CSC is in fact

redundant or actually eliminated many false-positive major depression

diagnoses became key to the debate, which is still ongoing, about the

prevalence of depressive disorder.

The latest study, coming in the American Journal of Psychiatry,

offers

an empirical demonstration, based on nationally representative

data, that the Critical Significance Criterion fails to distinguish

normal from disordered conditions. In this analysis, Wakefield

undertook to evaluate independently the impact of the CSC on

epidemiological survey estimates of major depressive disorder by using

data from a later survey that included a carefully worked out CSC

criterion for depression whose inclusion, according to the claims of

its authors, was an effective way of eliminating former false

positives. Wakefield then compared estimates of depressive disorder

with and without the use of the CSC. Confirming the redundancy

hypothesis put forward a decade earlier, he found that the CSC

eliminated virtually no one from diagnosis—in fact, even among those

who experienced prolonged sadness without meeting other diagnostic

criteria for depression, about 94% of them satisfied the CSC just on

the basis of the "distress" component alone. Thus the Clinical

Significance Criterion, according to Wakefield and his co-authors, is

not doing what it is supposed to do – reducing the over-diagnosis of

normal mood fluctuations as depression – and the issue of preventing

false positives needs to be revisited. And contrary to critics'

speculations, the earlier findings suggesting many false positives in

community surveys cannot be dismissed on the basis of the CSC.

The results take on further importance, Wakefield says, in light of

proposals for changes to the DSM in a revision currently taking place

that will lead to DSM-V. Concern about increasing false positives is at

the heart of criticisms of the proposals that have been put forward by

leading psychiatrists, including Frances, the Editor of DSM-IV.

Moreover, some of the proposals seem to rely heavily on the CSC to

justify diagnosis of disorder even when symptoms are minimal—when in

fact the current research underscores that normal distress can easily

satisfy the CSC.

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To see the research abstract, please visit http://ajp.psychiatryonline.org/cgi/content/abstract/appi.ajp.2009.09040553v1