An Ecological Momentary Assessment Study Examining the Efficacy of Third-wave Cognitive Behavioral Therapies on Different Indices of Pain-related Outcomes

Objectives: The average level of outcomes is the most used index for assessing the efficacy of psychological therapies; however, emerging evidence suggests that it may not fully capture the complexity of treatment effects. This study compared the effects of third-wave cognitive behavioral therapy (CBT) on pain-related outcomes (pain intensity, pain interference, sleep disturbance, and depressed mood) using six indices: average level, variability, maximum level, minimum level, frequency in high, and frequency in low. Methods: Ecological momentary assessment (EMA) data were collected within a randomized controlled trial (RCT) that evaluated the addition of remote-delivered third-wave CBT to treatment-as-usual (TAU) in individuals with chronic low back pain plus depressive symptoms. A total of 82 participants (CBT = 50 and TAU = 32) provided 4,595 EMA data points over 10 weeks (70 days). Results: Compared to TAU, third-wave CBT was generally associated with greater improvement across the pain-related outcomes. Frequency in low emerged as the most sensitive index for change in pain interference and depressed mood; in contrast, the average level showed limited sensitivity. The maximum level also captured some between-group differences for sleep disturbance and depressed mood. The remaining indices (variability, minimum, and frequency in high) did not consistently provide additional value. Discussion: These findings suggest that the frequency in low may be a sensitive and clinically informative index for detecting treatment effects in RCTs using EMA. Nevertheless, further research is needed to establish its reliability and generalizability across clinical contexts and clinical trial designs.