Clinical Significance of the Outcome Questionnaire (OQ-45.2)‪.‬

The Outcome Questionnaire-45.2 (OQ-45.2) is purported to measure important areas of functioning (symptoms, interpersonal problems social role functioning and quality of life) that are of central interest in mental health. In recent years research employing the OQ-45.2 has focused on tracking patient change over time and indicating if and when patients return to a normal state of functioning as proposed by criteria for clinically significant change. This study examined the OQ-45.2 cut-off scores for clinical significance by comparing concordance rates with cut-off scores based on other measures of psychotherapy outcome. Instruments of each area of functioning were administered to patients undergoing psychotherapy at the beginning and end of treatment. Each patient's degree of success was then classified by each instrument and differences between the measures were examined. The results provided evidence for the construct validity of the concept of clinical significance and the OQ-45.2 cut-off scores demarking the boundaries for functional/dysfunctional samples. Correspondence between measure estimates for classifying patients as functional or dysfunctional averaged 85%. Estimates of agreement between measures classification of patients as meeting criteria for clinically significant change averaged 65%. Implications of these results were discussed in reference to use of the OQ-45.2 and the concept of clinical significance. **********