Unidimensionality of the Brief Symptom Inventory (BSI) in adult and adolescent inpatients.

This study investigated the factor structure of the Brief Symptom Inventory (BSI; Derogatis, 1992) for adult and adolescent psychiatric inpatients. The BSI was administered to 217 adults and 188 adolescents at admission and discharge from a private psychiatric hospital. Principal components factor analyses revealed that most variance among dimension scores was accounted for by one unrotated factor. Factorial invariance was evident across adult and adolescent samples for admission and discharge scores. Our findings are consistent with previous research on the BSI and Symptom Checklist-90-R (Derogatis, 1977), suggesting that both instruments measure primarily a unidimensional construct of general psychological distress.