CHRONIC – A Digital Multimodal Pain Intervention: Study Protocol for a Randomized Controlled Trial (Preprint)

BACKGROUND Chronic pain affects approximately 12 million individuals in Germany and significantly impairs quality of life. Although multimodal treatment approaches—combining physical, psychological, and behavioral strategies—are considered the gold standard, long waiting times for psychotherapy limit timely access to care. Digital health interventions, particularly those grounded in established therapeutic models, offer a promising solution to bridge this treatment gap. The German Digital Health Care Act (DVG) has opened pathways for reimbursable digital applications such as CHRONIC, which uniquely integrates cognitive behavioral therapy (CBT), Acceptance and Commitment Therapy (ACT), mindfulness, and physiotherapy into a structured web-based program. OBJECTIVE This study protocol outlines a randomized controlled trial aimed at evaluating the effectiveness of CHRONIC, a 12-week web-based, multimodal self-help program for individuals with chronic pain, with a focus on reducing pain-related interference and improving quality of life. METHODS This is a monocentric, three-arm randomized controlled trial (RCT) with pre-, post-, and three-month follow-up assessments. A total of N = 200 participants with chronic non-malignant pain will be randomized into one of three groups: (1) intervention with individualized psychological feedback (EGpsych), (2) intervention with standardized computer-generated feedback (EGcomp), and (3) treatment-as-usual waitlist control (TAU). Weekly modules in the intervention arms include psychotherapeutic video sessions, interactive ACT- and CBT-based exercises, mindfulness practices, and physiotherapeutic movement training. Outcomes will be assessed via validated self-report instruments: the WHYMPI for pain intensity and interference, AQoL-8D for quality of life, CPAQ-D for pain acceptance, PHQ-9 for depression, and GAD-7 for anxiety. Data will be analyzed using repeated measures ANOVAs with intention-to-treat and per-protocol approaches. Missing data will be addressed using multiple imputation. RESULTS Recruitment not yet started; no results available. Primary outcomes include reductions in pain-related interference and improvements in quality of life from pre- to post-intervention and follow-up. Secondary outcomes include increases in pain acceptance and reductions in depressive and anxiety symptoms. Differences between the two feedback formats will be explored to assess the added value of individualized therapist feedback over computer-generated feedback. CONCLUSIONS This study protocol describes a randomized controlled trial designed to evaluate the clinical utility of CHRONIC as a scalable, low-threshold intervention for chronic pain. By combining psychotherapeutic, physiotherapeutic, and mindfulness-based strategies in a digital format, CHRONIC is expected to address the multifactorial nature of chronic pain more comprehensively than existing unimodal tools. The findings aim to inform future digital health developments and contribute to the implementation of biopsychosocial care models in routine practice. CLINICALTRIAL German Clinical Trials Register (DRKS), ID: DRKS00036901. Registered on July 17, 2024.