Identifying an efficient psychotherapy outcome scale to use with outpatient mental health populations

Rena M. Popma (1998)

An easily available, inexpensive, brief measure of adult general outpatient functioning with good psychometric properties does not exist. Thus, this study sought to create such a measure. Five measures gathered for 159 adults (age 17 or older) at 10 private practice settings were used in this study. Factor analysis of the responses to all items of five client measures (the Brief Symptom Inventory (BSI; Derogatis & Spencer, 1982), the Client Rating Scale (derived from Target Complaints, Mintz & Kiesler, 1982), a Daily Routine Scale (Warheit & Buhl, 1979), a General Distress Scale (derived from Dupuy's General Well-Being Scale, Fazio, 1977), and the Dissociative Scale (derived from the Dissociative Experiences Scale, Bernstein & Putnam, 1986)) was done, and five factors emerged. Items that had the highest loading on each factor were retained in an item pool. These 30 items were subjected to Multiple Regression analyses to predict four of the original measures. Those 13 items that predicted the original measures at.80 or greater were retained to create the Outcome Assessment Scale (OAS). The total score on the OAS was correlated with the total scores of the original measures and with total scores on client satisfaction and therapist measures as a validation procedure. Reliability was measured using the Spearman-Brown Split-Half reliability test. The 13-item OAS correlated.82 or greater with BSI, Daily Routine, Well-Being, and Client Rating. The OAS appears to be a psychotherapy outcome assessment instrument that can provide a much shorter alternative to available instruments. Further, the OAS provides information from a number of domains of functioning that would otherwise require administering several measures.