Costello et al (1985) looked at the performance o f the DISC in comparing different
treatment groups. The DISC was administered to 40 psychiatric out-patients and 40
paediatric controls aged between 7 and 11. Using the child interview and mild or severe
diagnoses, the DISC correctly identified 25% of the paediatric referrals and 95% of the
psychiatric group. Using the child interview and severe diagnoses only, the DISC
identified 85% o f the paediatric referrals and 45% of the psychiatric referrals. The
authors reported that if one only considers the severe diagnoses the sensitivity (i.e.ability
to identify “cases”) o f the DISC was 45% overall. The specificity o f the DISC (i.e.ability
to correctly identify “non cases”) using the severe diagnoses was 80%. Using the severe
or mild/moderate diagnoses the DISC sensitivity was 95% but the specificity was low at
25%. The low specificity appeared to be because the children in both groups reported
many mild disorders.
The d i s c’s ability to discriminate between the two treatment groups was more clear with the symptom complex scores. The psychiatric group had higher scores with regard
to the combined anxiety scale (although there were no significant differences between the
groups on Overanxious Disorder), Fears and Phobias, (although not Social Phobia)
Schizoid/Psychotic scores. Affective symptoms and the total number o f symptoms. There
were, however, no significant differences with regard to Obsessive Compulsive
symptoms. Costello et al (1985) argued that the DISC’s ability to discriminate between
the treatment groups was clear for the DISC symptom complexes but less clear for the
diagnoses themselves. They pointed out that when the DISC algorithm followed DSM
III diagnostic criteria very rigidly and the mild/moderate level o f diagnosis was in
more stringent set of criteria were used to assign the diagnosis, a significant difference
between the groups was observed. The authors suggested that the classification on which
the DISC interview was based required revision and that these data indicate that DSM
III criteria have limited validity.
Psychometric data on the detection o f eating disorder by diagnostic interviews has only
been published in one paper. A study on the validity the DISC-R was conducted by
Fisher et al (1993). The aim of the study was to investigate the sensitivity of the DISC-R
in its detection o f more rare disorders. The authors recruited the following groups from
treatment centres specialising in the treatment of a number o f disorders:
i)61 in-patients and 15 out-patients with either DSM III-R Anorexia or Bulimia Nervosa
and between 12 and 17. The diagnosis was done by non standardised clinical assessment.
ii)l 1 out-patients with DSM III-R Major Depressive Disorder aged between 9 and 17.
The diagnosis was done by a clinician using the K-SADS. The mean duration between
the K-SADS and DISC-R was 28 days.
iii)17 patients with DSM III-R Obsessive Compulsive Disorder (patient status not
specified). The diagnosis was made by a non standardised clinical assessment.
The authors also recruited patients with TIC Disorders and Substance use Disorders.
Data on these patients have not been included here as they are not within the remit o f the
present thesis.
Fisher et al (1993) reported that the sensitivity of the DISC-R in a clinical setting was
adequate for Anorexia Nervosa, ( 67% ), Bulimia Nervosa (75%) and Obsessive
Compulsive Disorder (65%). However, the DISC-R had poor sensitivity for the
detection o f Major Depressive Disorder (18%). The authors reported that it became
apparent that the wording of the Major Depressive Disorder items were complicated and
needed to be revised. They pointed out that the DISC-R was different from the K-SADS
and DICA in that the DISC-R required that some of the symptoms co-occurred during a
the DISC-R was poorer than other interviews in the detection o f Major Depressive
Disorder as the other validity studies have tended to look at affective disorders in general
rather than specific diagnoses.
Hodges et al (1982) compared nine o f the CAS symptom complex scores across three
groups, 32 out-patients and 18 in-patients with Behavioural Disorders and 37 “normal”
controls. All three groups were aged between 7 and 14. The authors reported that there
were differences between the scores o f the three groups for eight o f the nine symptom
complexes compared. In terms of the symptom complexes that relate to the emotional
disorder, the in-patients had higher scores than the out-patients who in turn had higher
scores than the controls. The in-patients had higher scores than the out-patients and
controls combined, although there were no significant differences between the latter two
group on the Separation Anxiety symptom complex. Lastly with regard to the
Overanxious Disorder symptom complex, the in-patients and out-patients combined had
higher scores than the controls and the in-patients had higher scores than the out-patients
and controls combined. These data suggests that the depression symptom complex was
able to discriminate between all three groups and discrimination between in-patients and
controls was possible for the Separation Anxiety and Overanxious Disorder symptom
complexes o f the CAS. Hodges et al (1982) reported that the CAS total score was able
to identify 72% of the in-patients, 41% o f the out-patients and 84% of the controls. This
corresponded to an overall correct classification rate o f 66%.