Stability of the ADI-R
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Mean group scores for RSI and NVC domains and for total ADI-R score decreased significantly
between T1 and FU (see Table 3). The decrease in the VC score did not reach significance (likely due
to low N) and no significant difference was identified on the RBSP domain.
(Insert Table 3 about here)
In order to examine the extent of change shown by individual children, ADI-R change (FU-T1) scores
at domain and total score level were divided into quartiles (see Figure 1 for details of quartile ranges in
each domain and the total ADI-R score). Although some children made ‘moderate’ to ‘major’
improvements in each of the domains assessed, many showed no or only ‘minor’ change.
(Insert Figure 1 about here)
Item level scores
Stability of ADI-R item level scores between T1 and FU was assessed within each domain (RSI, NVC,
VC and RBSP). Typically scores of 2 and 3 are collapsed in the algorithm output for the ADI-R. For
the purposes of this analysis, the distinction between scores of 2 and 3 was retained in order to ensure
that any change over time could be identified. Analysis on verbal items was conducted only for those
individuals who were verbal at initial assessment (N= 7). Figure 2 illustrates the mean item level scores
of items in the RSI, NVC, VC and RBSP domains of the ADI-R at T1 and FU2.
(Insert Figure 2 about here)