Discriminating maintenance treatments for recurrent depression : development and implementation of a rating scale

A 27-item therapy rating scale was developed to evaluate therapists' use of two maintenance treatments for recurrent depression: Maintenance Interpersonal Psychotherapy (IPT-M) and Medication Clinic. Analyses of data obtained from student raters indicated that 13 items discriminated between the two therapies (P0.05). Split-sample discriminant function analysis using these items accurately classified 83% of index-sample sessions and 80% of validation-sample sessions. Factor analysis yielded four modality-specific factors, two contamination factors, and one general psychotherapy factor. Four factors related to therapeutic intervention and session focus differentiated IPT-M from Medication Clinic. Findings confirm the psychometric adequacy and sensitivity of the scale; possible use in predicting patient outcome is discussed.