Does Intensive Interdisciplinary Pain Treatment (IIPT) Enhance Endogenous Pain Modulation in Youth with Chronic Pain Syndromes?

Objectives: This study aimed to investigate whether endogenous pain modulation improves after intensive interdisciplinary pain treatment (IIPT) and its relationship with clinical outcomes in youth with chronic pain syndromes. Endogenous pain modulation is a physiological process in the nervous system that inhibits pain perception. Endogenous pain modulation is often impaired in youth with chronic pain syndromes and is a potential mechanism by which IIPT interventions act. Methods: Endogenous pain modulation was measured using offset analgesia (OA) in 27 youth with primary and secondary chronic pain syndromes before and after IIPT. Test-retest reliability was measured in a subset of participants (n=12) within 5 days of IIPT admission to examine whether the observed change was meaningful and beyond the limits of error. Results: On average, OA response improved by 12.4% between admission and discharge (95% CI: 3.0, 21.8%), even after controlling for covariates using a mixed effects multivariable repeated measures ANOVA ( P =0.009). OA responses demonstrated excellent test-retest reliability, intraclass correlation coefficient=0.919 (95% CI: 0.718, 0.977), and minimum detectable change (MDC 95 ) of the OA response was 13%. Participants also demonstrated an improved ability to adapt to a constant noxious heat stimulus ( P =0.044) that moderately correlated with improvements in self-reported pain intensity and sensitivity to stimuli ( P <0.05). Discussion: Overall, 52% of participants demonstrated meaningful improvements (i.e., change greater than the MDC 95 ) in endogenous pain modulation after IIPT participation. The contributions of specific IIPT interventions (e.g., exercise, desensitization, cognitive behavioral therapy) to improvements in endogenous pain modulation need further exploration.