Stability of the ADI-R
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Discussion
The purpose of the current study was prospectively to assess the stability of ASD symptomatology,
according to the ADI-R, from pre-school to elementary school in a group of children with a wide range
of intellectual and verbal ability.
No statistically significant changes in the number of participants meeting autism criteria on the ADI-R
between T1 and FU were identified at domain or total score level. All of the 35 children selected for
participation met full ADI-R criteria for autism at T1, including criteria for abnormality before 36
months. At FU, 28 children met full ADI-R criteria for autism based on their current behaviour. Since
all the children had also received an independent diagnosis of ASD from a qualified clinician prior to
inclusion in the study, this stability in ADI-R classification also reflects the overall reliability of early
clinical diagnosis (see also Stone et al., 1999; Eaves & Ho, 2004; Moore & Goodson, 2003). However,
in common with other recent studies that have examined stability of clinical diagnosis (Sutera et al.,
2007; Turner & Stone, 2007); some children who initially met ADI-R criteria for autism later on only
met criteria for broader ASD or fell below even the ASD threshold. Although clinical diagnosis was
not re-ascertained in the current study, either by the research team or the children’s local clinicians at
FU, all children still presented with behaviours associated with ASD and most showed significant
impairments and delays in their development and functioning. .
The stability of ADI-R classification was greater in the present study than in that of Charman et al.
(2005). Charman et al. reported that between the ages of 2 and 7 years, 14 children out of the 26
participants changed ADI-R classification at least once, 5 changed status twice and one child (with a
clear clinical diagnosis of autism) was given a different ADI-R classification on each of the 3
assessments. Charman et al. (2005) suggested that these changes might be attributable to other factors