IPDE - Extranet Systems - World Health Organization

Discussion and Conclusions
of principal investigators in Geneva. The only significant reservation
about the interview shared by a majority of the interviewers concerned
its length. This was a necessary consequence of the decision to systematically
inquire about all of the PD criteria in the ICDIO and DSM-In-R
classification systems. The mean length of the interview was 2 hours 20
minutes, and there was considerable variation around that figure. If a
patient acknowledged many criteria, the subsequent inquiry for confirmatory
examples and anecdotes prolonged the interview. If few of the
behaviors were endorsed, then the IPDE went comparatively rapidly. If
it became evident that the interview was likely to exceed more than one
and a half to two hours, an effort was made to administer it in more than
one sitting to prevent erosion of the quality of the interview from fatigue
or boredom.
To offset the concern about the length of the interview and to make it
more acceptable to a wider range of clinicians and investigators, it was
decided to issue it in modules and to update the DSM-111-R component
to conform to DSM-N. While the longer version of the IPDE assesses
all of the disorders in ICD-10 and DSM-IV, separate modules are available
for those who wish to l i t the examination to only one of the two
classification systems. Those concerned with only certain selected disorders
within one of the two systems can also restrict the interview to those
items relevant to the disorders of interest to them.
A self-administered screening version of the IPDE is also available. It
is not intended to substitute for the interview, because the literature
indicates that PD inventories and inte~ews do not provide equivalent
diagnoses. The screening inventory merely makes it possible to avoid
interviewing those who are unlikely to receive a PD diagnosis on the
interview. A field trial was undertaken with an early screening version
of the DSM-In-R module in a sample of 258 university ~tudents.'~ The
inventory produced few false-negative cases vis-d-vis the interview,
but as expected it yielded a high rate of false-positives. Of course,
the low literacy rate in some nations precludes its use with certain
populations.
Whereas reliability refers to the consistency with which a diagnosis is
made, validity refers to the accuracy of the diagnosis. The problems
associated with establishing the validity of either an ordinary clinical
interview or a semistructured one such as the IPDE are formidable. What
should one use as the 'gold standard? It would be. meaningless to validate
the IPDE against clinical diagnosis without first having established
the reliability if not the validity of the clinicians themselves. If clinical