1. OCD: issues surrounding
classification and diagnosis
• There are several issues
surrounding the classification and
diagnosis of OCD that need to be
assessed.
• These include addressing issues
surrounding the reliability and
validity of diagnosis.

2. DSM- IV
• The Diagnostic and
•
•
Statistical Manual of
Mental Disorder (Edition
4), was last published in
1994.
The DSM is produced by
the American Psychiatric
Association.
It is the most widely used
diagnostic tool in
psychiatric institutions
around the world.

3. ICD - 10
• There is also the
•
International
Statistical
Classification of
Diseases (known as
ICD).
It is produced by the
World Health
Organisation (WHO)
and is currently in
it’s 10th edition.

4. Labelling
• Someone who has suffered
•
a mental disorder has to
disclose that information in
situations such as job
interviews, or they could
face formal action.
Unlike influenza, the label of
‘mental illness’ stays with a
person.

5. Measuring obsessions and
compulsions
• There are scales for the measurement of general anxiety
and specific scales for the assessment of obsessions
and compulsions.
• According to RUSH (2007) the best is the Y-BOCS
devised by Goodman et al.
• This is a semi structured interview asking about
obsessions and compulsions and the extent to which
they affect everyday life.
• More recently Goodman has developed a new scale –
the Florida Obsessive-Compulsive Inventory.

6. Reliability and validity of DSMIV and ICD-10
• Diagnosing a mental disorder is almost always
•
•
done using the DSM-IV and the ICD-10.
However, there is a risk of using this
professional jargon. (Wording in the manuals is
written for specialists to understand, not
laymen).
The main issues surrounding the diagnosis of
mental disorders centre on the reliability and
validity of the diagnoses.

7. Reliability of Diagnosis
• This refers to the consistency of a measuring
instrument such as a scale to assess fear.
• It can be measured in terms of whether two
independent assessors give similar scores:
known as INTER-RATER RELIABILITY
• Patients are generally diagnosed on the basis of
one or more interviews with a therapist.

8. Inter-rater reliability and
test-retest reliability -do
bloke thinks?
psychiatrists agree?
I wonder
• Woody et al (1995) assessed
54 patients with OCD using
the Y-BOCS and found good
internal consistency. Interrater reliability was was
reported as excellent.
• However, test-retest results
after an average of 48 days
was lower than desirable.
Other studies have however,
found good test-retest
reliability.
what the
other
psychiatris
t thinks?

9. Findings on reliability
• Brown et al carried out two
interviews on 1400 patients
WITH A GAP OF TWO
WEEKS BETWEEN
INTERVIEWS. The inter-rater
reliability was excellent. The
most likely explanation is that
compulsions provide a clear
behavioural indication of the
presence of OCD. There were
some sources of unreliabilityThe main one was
• Differences in the symptoms
were reported by patients in
the two interviews.

10. More findings
• Steinberger et al compared DSM-IV and
•
ICD-10 in their diagnoses of
OCD. Found large differences
between the two systems
suggesting problems with
consistency of diagnosis.
Using DSM-IV 95% of patients
were diagnosed with OCD
compared to only 46% using
ICD-10 criteria.
The criteria for ICD-10 are less detailed and
clear so the DSM system is preferable.

11. Reliability of self report and
computerised versions of Y-BOCS.
• These appear to yield reliability scores
similar to interviewer-administered
versions.
• The children’s version has also been
shown to have good inter-rater reliability.

12. Validity of diagnosis
This considers whether the system of classification and diagnosis
reflect the true nature of the condition as something that is real and
distinct from other conditions.
Discriminant validity:
refers to the ability of a diagnosis to
distinguish between OCD and other conditions.
• OCD can resemble the delusional beliefs of schizophrenia when the
nature of the thoughts is bizarre.
• Obsessions and compulsions occur in a number of other disorders- e.g.
eating disorders/ body dysmorphic disorder/social phobias. DSM-1v
specifically warns clinicians not to diagnose OCD when the obsessions
and compulsions are restricted to another disorder.
• There can be some overlap between OCD and obsessive personality
disorder – this people who are inflexible, obstinate, rigid and apt to focus
on unimportant detail. They are frequently humourless and judgemental,
with a need for perfectionism and rigidity.

13. Validity - Distinguishing
between ‘worries’ and obsessions
• It is difficult to distinguish between
obsessions and simple ‘worries’ which are
not pathological (related to a mental
disorder.)
• Worries include things such as family,
finances and work.
• According to Brown (1993) most clinicians
can reliably distinguish between worries
and obsessions.

14. Validity of diagnosis
• It is possible that people may not produce honest
answers to questionnaires about their OCD symptoms
and this reduces the validity of any such questionnaire(may fear interviewer will think they have a deeper
mental illness or be embarrassed). It has been estimated
that only about 40% of people with OCD symptoms come
forward for treatment.
• Patients may also be fearful of handling questionnaires
because they fear they are dirty.
• A further problem is that some patients may
lack awareness of the severity and frequency
of their symptoms. Validity is likely to be
improved by interviewing close friends and partners.

15. Findings on Validity
• Rosenfield et al found that patients diagnosed
•
with OCD had higher Y-BOCS scores than
patients with other anxiety disorders and normal
controls – therefore it does distinguish OCD
patients from others.
However, Woody et al found poor discrimination
with depression – patients diagnosed with OCD
were often also diagnosed with depression and it
can be difficult to disentangle the two disorders.
(67% of people with OCD also have depression
– Gibbs)

16. Cultural Relativism
• The incidence of OCD tends to be the same in most
countries/cultures (about 2-3%.
• However the symptoms are often
shaped by a patient’s culture of
origin.
• For example a patient from India
may fear contamination by
touching a person from a lower
social caste.
• This may lead to problems with diagnostic scales because
symptoms checklists may be culturally based.

17. Cultural problems
• Williams et al 2005 demonstrated
that there were significant
differences between normal
populations of black and white
Americans in the scores for
contamination obsessions. Black
Americans have less interaction
with animals and have a greater
fear of contamination from them –
increasing the diagnosis of OCD.
• However – Matsunaga studied
Japanese OCD patients and found
symptoms remarkably similar to
those in the West – concluding that
OCD transcends cultures.

18. Conclusions about diagnosis:
Meehl (1977)
Suggests that mental health professionals
should be able to count on the diagnostic
tools if they:
–
–
–
Paid close attention to medical records
Were serious about the process of diagnosis
Took account of the very thorough
descriptions presented by the major
classificatory systems
– Considered all the evidence presented to
them.