Global measures of impairment in children and adolescents: results from a Swiss community survey.

OBJECTIVE: Based on data from a Swiss epidemiological survey, both the parent and the child versions of two global measures of impairment, the Columbia Impairment Scale (CIS) and the Children's Global Assessment Scale (CGAS) were analysed with regard to validity and the effects of gender.
METHOD: Concurrent and discriminant validity were evaluated by examining the associations with other indicators of impairment. Gender effects on impairment were considered in each type of analysis.
RESULTS: Based on the total sample and on the girls' data, concurrent validity of the various impairment scores as computed by correlations with other indicators of psychological dysfunction was good. When based on the boys' data it was less convincing. Discriminant validity was estimated by comparing impairment scores between those using and not using services and was proven for all impairment scores. There were significant gender effects for almost all scores, indicating that girls in contrast to boys were more impaired and functioned less well when professional contacts and psychiatric diagnosis were considered.
CONCLUSIONS: The two impairment measures are well suited to community studies. Gender and informant differences have to be considered when defining thresholds for caseness. The two scales could also be used clinically, for example for training and evaluation purposes and for the decision whether or not a child or adolescent requires treatment.