Symptom distress and disability: Different sides of the same coin? An investigation of the relationship between symptom distress and disability over time in patients receiving treatment for internalizing disorders

Background: Most psychotherapy outcome research focuses on symptom reduction as a primary outcome. However, most patients do not seek psychological treatment exclusively for symptom relief, but mainly because they can no longer do what they want to do or used to do. Therefore, besides symptom reduction, also disability in daily functioning should be a focus of psychotherapy outcome research. Yet, until now there is a paucity in research pertaining to the relation between symptom reduction and reduction of disability during psychological treatment. Aims: For this reason, the aim of the current study was to examine the relationship between changes in symptom reduction (reduction in general symptom distress) and changes in self-reported disability over a period of two years in patients that receive psychotherapy for mood and anxiety disorders (N = 1182). Results: We found strong correlations between both outcome measures at all measurement points. Furthermore, results demonstrated a decrease in both outcome measures from start to end of treatment with a moderate effect for symptom distress and a small effect for experienced disability. Cross-lagged panel analysis demonstrated that a decrease in symptom distress predicted a subsequent decrease in self-reported disability, and a decrease in self-reported disability equally predicted a subsequent decrease in experienced symptom distress. Conclusion: Our results seem to indicate that both outcome measures are interchangeable in psychotherapy outcome studies for internalizing disorders