Factorial structure of the 17-item Hamilton Depression Rating Scale.

The Hamilton Depression Rating Scale was applied to 60 depressed inpatients diagnosed using the Composite International Diagnostic Interview. The information to rate the scale was obtained with a semistructured interview to standardize the scale administration method. Items were factorized using principal components analysis with Varimax rotation. Three factors were obtained with the simulation method, accounting for 47% of variance. The first includes the core symptoms of depression. The symptoms of patients having an isolated mood disorder were compared with those having comorbidity with other diagnoses. The comorbidity did not affect the first factor but modified the second factor (anxiety) and the third factor (insomnia).