Dynamic assessment of pain and negative emotion during cognitive behavior therapy for chronic pain using ecological momentary assessment.

Affective, cognitive, and behavioral factors contribute to pain persistence and disability. Cognitive-behavioral therapy (CBT) is known to be useful in chronic pain treatment. Clinical trials of CBT have often used the average pain intensity as the primary outcome measure, which may overlook crucial day-to-day variability. Ecological momentary assessment (EMA) can capture momentary pain data, minimizing recall bias and enabling more detailed analyses. In this exploratory study (N = 136), we examined daily EMA data collected during group CBT (GCBT) for chronic pain (Clinical trials number; UMIN000010344). Participants provided daily ratings of pain intensity and negative emotion intensity throughout the treatment period. We performed multiple imputation (m = 100) to address missing data, and estimates were pooled using Rubin's rules. Pain intensity and negative emotion intensity significantly decreased over the treatment sessions. A random-intercept cross-lagged panel model analysis revealed reciprocal associations: higher pain intensity was associated with higher subsequent negative emotion intensity, and higher negative emotion intensity was associated with higher pain intensity the following day. Reducing the frequency of high-intensity pain and negative emotional episodes was also associated with improvements in pain and depressive symptoms after treatment. EMA-based session-by-session assessments offer subtle insights into treatment mechanisms and highlight the therapeutic value of addressing severe pain episodes and emotional fluctuations. These findings support integrating EMA to enhance outcome measures in clinical pain research. PERSPECTIVE: Ecological momentary assessment during CBT captured reciprocal, within-person temporal associations between pain and negative emotion and showed that reducing high-intensity episodes relates to better outcomes. EMA-derived indices may refine trial endpoints and guide therapies that target emotion regulation and severe pain peaks in chronic pain.