Abstract
<title>Abstract</title> <p>Background Chronic pain affects 20–30% of adults and poses a burden. Although cognitive-behavioral therapy (CBT) is the first-line psychological treatment, access barriers and limited durability have increased interest in digital interventions grounded in metacognitive principles. Objective To compare face-to-face CBT, a metacognitive app-based intervention (MCT-App; COGITO), and their combination on pain intensity, metacognitive beliefs, and pain catastrophizing in adults with chronic pain. Methods In this three-arm randomized controlled trial, 150 adults with physician-confirmed chronic pain (≥ 3 months) were allocated 1:1:1 to CBT, MCT-App, or Combined CBT plus MCT-App. CBT consisted of eight weekly 90-minute sessions, and MCT-App involved eight weeks of app use. Pain intensity (VAS; primary outcome), metacognitive beliefs (MCQ-30), and pain catastrophizing (PCS) were assessed at baseline, post-intervention, and one-month follow-up and analyzed using linear mixed-effects models. Results Of 150 randomized participants, 138 (92.0%) completed all assessments. Group × time interactions were found for VAS, MCQ-30, and PCS (all p < .001). No between-group differences emerged at post-intervention for VAS or PCS, although the Combined group showed improvement in MCQ-30 than CBT (β = −6.74, p = .008). At follow-up, the MCT-App-only group showed relapse in pain intensity and catastrophizing relative to CBT, whereas the Combined group maintained outcomes comparable to CBT. Conclusions Standalone app-based intervention produced short-term benefits comparable to CBT but was associated with relapse at follow-up. Combined CBT plus MCT-App preserved gains and produced clinically meaningful metacognitive improvement, supporting blended care as an adjunct rather than a replacement for therapist-led CBT in chronic pain management. Trial Registration: The study protocol was approved by the Research Ethics Committee of the University of Tabriz (Approval No.: IR.TABRIZU.REC.1404.068) and was registered in the Iranian Registry of Clinical Trials (IRCT20250727066648N1) on 13/08/2025.</p>