Critical consideration of assessment methods for clinically significant changes of mental distress after psycho‐oncological interventions

OBJECTIVES: Considering the heterogeneity of cancer entities and the associated disease progression, personalized care of patients is increasingly emphasized in psycho‐oncology. This individualization makes the use of measurements of individual clinically significant change important when studying the efficacy and effectiveness of psycho‐oncological care. Two conceptualizations for the measurement of clinical significance are critically contrasted in this study: the Reliable Change Index (RCI) and the Minimal Important Difference (MID) method. METHODS: In total, 2,121 cancer patients participated in the study and a subsample of 708 patients was reassessed about 4 months later. Psychological distress was measured using the Hospital Anxiety and Depression Scale. We evaluated two measures of clinical significance (RCI, MID) by comparing the respective numbers of improved, unimproved, and deteriorated patients. RESULTS: Individually significant changes were observed with both methods; however, determined rates of improvement differed substantially: MID (66.67%) and RCI (48.23%). Most importantly, according to MID, 17.93% of patients were identified as being improved, although their respective improvements were not statistically significant and thus unreliable. CONCLUSIONS: The benefits of RCI outweigh MID, and therefore, the RCI is recommended as a measure to assess change.