Objective: To describe the usefulness of impairment items placed at the end
of each diagnostic section of a structured instrument (the Diagnostic Inte
rview Schedule for Children Version 2.3) in an attempt to link impairment t
o specific diagnoses. Method: Data from 3 sites of the Methods for the Epid
emiology of Child and Adolescent Mental Disorders Study were used to assess
the reliability of the specific impairment measures by diagnosis, the exte
nt to which global and specific measures of impairment impact on prevalence
rates, the concordance between global and specific impairment, and the deg
ree to which there may be a "halo effect" among specific impairment ratings
. Results: Test-retest reliability was better for parent than youth ratings
. Fewer children were rated as impaired on well-validated global scales tha
n on specific impairment ratings, suggesting that the threshold for specifi
c ratings needs to be reevaluated. Agreement between specific and global ra
tings was poor. Most subjects with 2 or more diagnoses for which impairment
was attributed to one diagnosis also had impairment attributed to other di
agnoses for which they met symptom criteria, suggesting a halo effect in th
ese ratings of specific impairment. Conclusions: Impairment measures are im
portant in diagnostic assessments to distinguish those individuals whose ps
ychopathology is of clinical significance. Specific impairment ratings used
in structured instruments could be improved by including parameters of imp
airment that are diagnosis-specific.