IPDE - Extranet Systems - World Health Organization

A. W. Loranger
had more than one personality disorder, including 55 (15.0%) with two,
32 (8.7%) with three, and 24 (6.6%) with more than three disorders. Of
the 283 patients with an ICD-l0 personality disorder diagnosis, 96
(33.9%) had more than one type of disorder, including 57 (20.1%) with
two, 27 (9.5%) with three, and 12 (4.2%) with more than three disorders.
What are the implications of a patient having more than one form of
mental disorder, particularly more than one type of PD? In some
instances this may merely reflect the fact that twoor more disorders share
similar symptoms or diagnostic criteria. For example, subsme abuse
may be indicative of p r impulse control. a characteristic of antisocial,
emotionally unstable or borderline PD. Similarly, social withdrawal is a
diagnostic criterion shared by both schizoid and avoidant PDs. Another
implication may be pmgnostic or therapeutic, with one disorder modifying
the course or outcome of another. There is evidence, for example, that
depression is less responsive to treatment, when accompanied by a PD.
Comorbidity may also be a consequence of the fact that two disorders
share similar etiologies. Finally, at times comorbidity may also he an
indication of a defective or less thanoptimal classification system.
A fundamental problem in interpreting the meaning of the comorbidity
findings from various sNdies, including this one, is that they are
markedly influenced by the base rates of the disorders in the sample.
These in turn are a function of the admission practices of the facilities
from which the patients are drawn, not to mention the selection biases
for inclusion in the studies themselves. Ideally, comorbidity should he
determined from epidemiological studies based on probability samples
from the community. Unfortunately these rarely if ever include a suffi-
cient number of cases of most disorders, to provide definitive information
about the hue CO-occurrence rates of the disorders in question.
ICD-10 and DSM-IICR
As previously noted, ICD-10 and DSM-111-R are different but overlapping
classification systems. There are slight differences in nomenclature:
anankastidobsessive-compulsive, anxious/avoidant, and dissociaUantisocial.
In ICD-10 borderline and impulsive are viewed as subtypes of
emotionally unstable; schiwtypal is located with schizophrenia and
delusional disorders; and narcissistic, passive-aggressive, and the two
disorders in the appendix of DSM-111-R, sadistic and self-defeating, do
not appear. There are also several significant differences in the criteria in
the two systems and some minor variations in their wording. Except for