Departament de Psicologia de la Salut
Universitat Autónoma de Barcelona
A new scale for the assessment autistic
children is presented. The aim of this study is to develop a tool
with an easy and fast application and with useful screening method
of autistic syndrome that may be helpful in planning integrated
health and educational services.
The development of the items was done
according to the Diagnostic criteria for autistic syndrome DSM-III
(APA., 1980), DSM-III-R (APA., 1987) and CIE-10 (WHO., 1987).
A total of 15 ATA's items are representative of diagnostic críteria
for autistic syndrome, the other 8 aren't included in the diagnostic
criteria for autistic syndrome and they were collected from recent
research and clinical experience.
The ATA scale ("Escala d'Avaluació
dels Trets Autistes". Jané, Capdevila i Doménech,
1993), consists of 23 subscales. Each of them is provided with
a glossary explaining in a few words the significance of the items.
The ATA escale has been designed as parent/teacher/nurse report.
It has to be applied by a clinician psychologist/psyquiatrist
with experience in clinical practice with psychotic children.
The ATA scale isn't an interview, but a rating scale that provides
the children's behavioral profile . It's an observational tool
that allows a longitudinal pursuit of autistic symptomatology
development. Administration and scoring are relatively simple
and straightforward. The time necessary for its application is
brief (15-20 min.). The general rating of the ATA's scale are
made on a 3-point ordinal scale from 0 = within normal limits,
to 1 = infrequent or possible abnormality, to 2 definitive abnormality.
The ATA was created and validated in 1993. The development of the instrument and its standardization are described in the paper published in "Revista de Psiquiatría Infanto-Juvenil" Num.4 (1994). Psychometric properties were analysed and assessed according to three diagnostic criteria for autistic syndrome: DSM-III (APA., 1980), DSM-III-R (APA., 1987) and "The Childhood Autism Rating Scale" (CARS) (Schopler, DeVellis, Reichler, 1980).
The results of the studies according to DSM-III (APA., 1980) diagnostic criteria for autistíc syndrome showed a reliability tested by calculating the Kappa statistic (Fermanian, 1984) (Kappa = O.ll); the observed agreement (0.76) and the expected agreement (0.73). The results of the assessment of the observed quality showed a Sensibility (0.76), an Especificity (0.11), a predictive positive value (0.77) and a predictive negative value (0.50).
The results of the studies according
to DSM-III-R (APA., 1987) diagnostic criteria for autistic syndrome
showed a reliability tested by calculating the Kappa statistic
(Fermanian, 1987) (Kappa = -0.1); the observed agreement (0.89)
and the expected agreement (0.89). The results of the evaluation
of the observed quality showed a Sensibility (0.94), an Especificity
(0), a predictive value (+) (0.94) and a predictive value (-)
(0.50).
The internal reliability of the ATA was
0.81, as indicated by Cronbach's (1951) alpha. This reliability
index suggests that there is a high degree of internal consistency
among the items of the ATA.
The results of the studies presented
here show that the ATA scale is a useful screening tool for the
observation of autistic behavior. This was the reason to develop
a new validation of this scale according to DSM-IV (APA., 1995)
diagnostic criteria for autistic syndrome.
METHOD
The population consisted of 43 children
whose ages ranged from 4 to 18 years. Thirty four of the children
were boys (79.1%) and nine were girls (20.9%). All children were
attending a special educatíon program. Clinical diagnoses
were established using DSM-III and DSM-III-R criteria prior to
the scoring and analyzing of the ATA data. Diagnosis were assigned
by experienced clinicians on the basis of clinical assessment
and the analysis of available information.
Intelectual functíoning was determined
using standardized tests: "Brunet-Lezine scale" ( Brunet
& Lezine, 1971); " The Weschler Intelligence Scale for
Children" (WISC) (Weschler, 1974); "Terman-Merrill Scale
of Mental Tests" (Terman & Merrill, 1966). IQ. ranged
from 20 to 70 {IQ<20 (7%); 20<IQ<50 (46.5%); 50<IQ<70
(27.9%); IQ>70 (9.3 %)}.
Family socioeconomic status (SES) was calculated using the Hollingshead (1975) scale: 2.3% of the families were upper social class, 9.3% lower-middle class, 67.4% lower class and 16.3% not known.
For the present study, ATA was administered
by a child psychologists with experience in the application of
ATA scales.
Each child was tested individually. The
realiability was calculated by kappa statistic ( Fermanian, 1984)
and the internal reliability tested by Cronbach's alpha
(1951).
RESULTS
EXTERNAL VALIDITY
The result of the studies according to
the DSM-IV (APA., 1995) diagnostic criteria for autistic syndrome
showed a reliability of 0.71 as calculated by the Kappa
statistic (Fermanian, 1984).
The internal reliability of the ATA was
0.81 as indicated by Cronbach's (1951) alpha.
The reliability index suggests that there
is a high degree of internal consistency among the items of ATA
as well as a high degree of agreement among the ATA and DSM-IV
(APA., 1995) criteria for autistic behavior diagnostic.
INTERNAL VALIDITY
The results of the evaluatíon
of the observed quality showed a Sensibility (100%), an Especificity
(50%), a predicted value (+) (95.12%) and a predictive value (-)
(100%). The efficient global index rated (90.69%). The present
results suggest that ATA is a tool with a high sensibility, middle
especificity and high efficient global index according to DSM-IV
criteria (APA., 1995).
DISCUSSION
The aim of this study was to spelling
the psychometric properties to the "Escala d'Avaluació
dels Trets Autistes" (ATA) according to DSM-IV diagnostic
criteria for autistic syndrome.
In considering the results it is important
to note that ATA was developed as a screening instrument to identify
Autistic Behavior. The analysis of the comparative study ATA scale
DSM~IV (APA., 1995) diagnostic criteria indicated that scale ATA
presents a high sensibility (100%), middle Especificity (50%),
high predicted value (+) (95.12%) and high predicted value (-)
(100%).
In the comparative study psychometric
properties of scale ATA according DSM-IV (APA., 1995) diagnostic
criteria and the results of the psychometric properties of ATA
according to DSM-III (APA., 1980) and DSM-III-R (APA., 1987) diagnostic
criteria, we may affirm that the psychometric properties of ATA
according to DSM-IV (APA., 1995) diagnostic criteria are
very good, in special for the Especificity and the predictive
values (_).
In conclusion it is suggested that agreement among the scale ATA and DSM-IV (APA., 1995) is the best.