Zealously over or under?
Medical Observer
Has
the effort to correct the problem of underdiagnosis of bipolar disorder
shifted too far in the opposite direction? Lynnette Hoffman reports.
LAST
spring two parents in a seaside village in Massachusetts were convicted
of murdering their four-year-old daughter by administering a lethal
combination of a high dose of clonidine and an antihistamine.1,2
The
little girl, Rebecca Riley, had been diagnosed with bipolar disorder at
the age of two, and along with clonidine, she’d also been taking the
antipsychotic quetiapine and the mood stabiliser divalproex sodium (not
available in Australia).
But as details of the case emerged, it wasn’t just the actions of the girl’s parents that had people concerned.
Earlier
this year the psychiatrist who made the diagnosis and prescribed the
medications settled a medical malpractice case for $2.5 million, which
will go to the girl’s two siblings, who had also been diagnosed with
bipolar disorder.3
Court testimony portrayed the
psychiatrist as having been duped into a diagnosis of bipolar disorder
by cunning parents who wanted to silence their children. After the
girl’s death the psychiatrist voluntarily stopped practising, but the
licensing board permitted her to resume practice and she is now back at
work.
It’s an extreme example of a diagnosis gone wrong, and so
far no such cases have cropped up in Australia. But some psychiatrists
say that while we haven’t reached those extremes, there is a worrying
trend toward doctors being persuaded by patients’ own self-diagnosis of
bipolar disorder, or desire for immediate treatment – even if there’s
not sufficient evidence to support it.
Historically, the biggest
concern has been underdiagnosis of bipolar disorder. But Professor Gin
Malhi, head of psychological medicine at the University of Sydney and
editor of the Australian and New Zealand Journal of Psychiatry, says
while cases of bipolar disorder do continue to go unrecognised,
overdiagnosis is becoming a problem of equal or possibly even greater
proportions.
“I think the threshold for diagnosing bipolar II disorder, in particular, has dropped,” Professor Malhi says.
“The
zeal for the underdiagnosis of bipolar disorder has led to
overdiagnosis in certain circumstances… It just reflects really that we
don’t have a very good mechanism to diagnose, hence we’re losing at both
ends.
“People who have clear mania, clearly are bipolar, but
there are other kinds of symptoms that can look like mania or overlap
with mania.
“The temptation is to define people with depression
and very occasional periods of feeling high or elated as having bipolar
disorder.”
Another prominent psychiatrist who shares Professor
Malhi’s concerns is University of New South Wales professor of
psychiatry Philip Mitchell, who articulated the complexities of
balancing early but accurate diagnosis in a paper he co-wrote for the
MJA last year.4
Professor Mitchell points to an American
study published in 2008 in which 700 psychiatric outpatients at a
hospital in Rhode Island were interviewed with the Structured Clinical
Interview for DSM-IV (SCID).5
Less than half the
patients who had previously been diagnosed with bipolar disorder by a
health professional received that diagnosis based on the SCID test.
Data
collected about their family history (which those diagnosing were
blinded to) showed that patients with SCID-diagnosed bipolar disorder
had a significantly higher morbid risk of bipolar disorder than patients
who self-reported a previous diagnosis of bipolar disorder not
confirmed by the SCID.
In fact, patients who told doctors they
had bipolar disorder, which was not diagnosed using SCID, had the same
morbid risk for bipolar disorder as those patients without bipolar
disorder.
Like Professor Malhi, Professor Mitchell believes that
patients are being diagnosed who don’t fulfil the criteria, “even broad
criteria”.
Whereas traditionally the criteria for diagnosing a
hypomanic episode consisted of at least 2–4 days of elevated mood, that
has been expanded to encompass a few hours or a day of elevated mood,
Professor Mitchell says.
“A number of websites around the world
have these checklists based on the Mood Disorder Questionnaire, so
patients are incorrectly labelling periods of normal enthusiasm and
excitement as hypomania.
“They’re coming to their doctors saying
‘I have bipolar disorder’, so I think the problem is patients are
self-diagnosing and I think medical practitioners need to be much more
critical… Clinicians need to use their own skills and judgement,” he
says.
Both experts say more context is needed to diagnose bipolar
disorder and doctors need to use their clinical judgement and be
critical, rather than treating the DSM-IV as an authoritative checklist.
They
say that while certain characteristics may indeed raise the risk of
bipolar disorder, they should be treated as such – and monitored closely
with a longitudinal approach rather than jumping into treatment
prematurely.
However, it would be misleading to claim the views
of specialists such as Professors Mitchell and Malhi are unanimous in
the field.
Professor Gordon Parker, executive director of the
Black Dog Institute, has written numerous papers about the dangers and
prevalence of unrecognised bipolar disorder, and he is among those who
say the broader criteria still produces accurate results.
“The
current duration of mandated highs in the DSM does not accord with
clinical observation, and many studies are showing that brief highs of a
day or so do not differ by severity or clinical features from highs
lasting a week or longer,” Professor Parker says, pointing out that the
DSM-5 is set to reduce the criteria for minimum duration as well.
Along
with distinctive highs, above and beyond normal happiness, Professor
Parker says features such as a ‘bulletproof’ lack of anxiety, as well as
the patient’s retrospective awareness of the consequences – such as
spending large amounts of money or major sexual indiscretions – and the
feelings of guilt and shame that follow, are among the features that
differentiate hypomania.
As for the Mood Disorders Questionnaire
and Mood Swings Questionnaire screen tests, when used in patients with
depression (as opposed to the general community) their accuracy for
bipolar disorder is about 80%, Professor Parker says.
“Bipolar II disorder possesses categorical mood-related features that are distinct from normal happiness and unhappiness.
“It is associated with the highest suicide rate of all psychiatric conditions – largely reflecting failures to diagnose.”
Professors Malhi and Mitchell don’t dispute the importance of timely and accurate diagnosis of bipolar disorder.
But
they say the problems associated with overdiagnosis are not merely
academic.“Bipolar disorder is a serious diagnosis with stigma attached,
and the side effects of medications can be quite severe – so you want to
be sure that only those patients who need them, get them,” Professor
Mitchell says.
“Patients [with broadly defined mania symptoms]
will be given the same medications as patients are given for
clear bipolar disorder. The difficulty with these lower thresholds is
there’s no evidence that these patients actually benefit from the mood
stabilisers.”
Making a bipolar disorder diagnosis*
For patients experiencing a major depressive episode with no clear
prior episodes of hypomania or mania, Professor Mitchell and his
colleagues recommend doctors forgo making an immediate diagnosis and
instead take a “probabilistic approach” looking at specific features
that indicate greater risk of developing bipolar disorder. These
include:
- Depressed patients with an ambiguous past history of hypomanic or manic episodes
- ‘Unipolar depressed’ patients with a family history of bipolar disorder
-
Young patients presenting with recurrent depressive episodes only
(where it is unclear whether this represents a first presentation of
bipolar disorder or unipolar depression)
- “At present, we do not
recommend that clinicians immediately diagnose and treat depressed
patients with these features as definitely having bipolar disorder, but
commend practitioners to seriously consider this possibility for such
individuals as treatment progresses,” the authors write.
Further, they recommend watching closely for early warning signs of manic or depressive episodes.
Possible warning signs for manic episodes:
- Increased activity and busyness
- Reduced need for sleep
- Impulsive behaviour
- Speaking in a caustic manner
- Telephoning friends indiscriminately.
Possible warning signs for depressive episodes:
- Feeling tearful, moody, withdrawn, snappy, slowed down, negative, stubborn, pessimistic, hopeless or excessively self-doubting
*MJA 2010; 193: S10–S13
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