Outcomes Assessment in Psychological Treatment: Spanish adaptation of OQ-45 (Outcome Questionnaire)

Abstract

Introduction: The Lambert’s Outcomes Questionnaire (OQ-45) is a 45-item self-administered instrument used to measure clinical outcomes in psychotherapy. It measures functioning through three areas: symptoms distress, interpersonal relations and social role. The objective of this paper is to assess the reliability and the validity of its Spanish version. Method:A sample of 639 subjects, non-clinical and clinical, completed the instrument. Results: The psychometric evidences of the questionnaire showed an adequate internal consistency (.97 and .91) and acceptable convergent validity with the BDI, STAI, PSS and SF-12. The Confirmatory Factor Analyses suggested a bifactor structure. The cut-off points have been established for the subscales and total score (54.5), considering the clinical criterion, which means, prioritizing slightly the sensibility over the specificity. The RCI was 3.80 and Minimum Change Score 17.56. Conclusion: The OQ-45 showed acceptable psychometric properties, providing support for using this version of the questionnaire to assess Spanish’s functionality. Given these findings, this tool could help clinicians evaluate treatment efficacy and establish psychotherapy goals.