Digital Therapeutic for Hwa-Byung (Korean Culture-Related Anger Syndrome) Based on Acceptance and Commitment Therapy: A Pilot Feasibility Trial

Background/Objectives: Hwa-byung (HB) is a culture-bound syndrome characterized by prolonged suppression of anger and somatic complaints. No evidence-based digital therapeutic (DTx) has been developed for HB. We evaluated the feasibility, user experience (UX), and preliminary clinical effects of an acceptance and commitment therapy-based DTx, Hwa-free, for HB. Methods: Adults aged 19–80 years diagnosed with HB were enrolled in a four-week app-based intervention with assessments at Weeks 0, 2, 4, and 8. The primary outcome was UX via a 22-item survey at Week 4. Secondary outcomes included HB scales, depression, anxiety, anger, psychological flexibility, and health-related quality of life. Results: Of 45 screened, 30 were enrolled; 28 constituted the modified intention-to-treat population. Mean app use was 20.3 ± 7.8 days (72.6% adherence). All adverse events were assessed as probably or definitely unrelated to the intervention. UX positive response rates exceeded 80% across video content (82.8–89.7%), HB self-assessment (86.2%), meditation (86.2%), and in-app guidance (85.7%). Within-group changes at Week 4 were observed in 11 of 18 clinical scales, including HB Symptom Scale (Δ = −9.8, d = −0.92), Beck Depression Inventory-II (Δ = −13.3, d = −1.11), and state anger (Δ = −7.8, d = −0.96); these are uncontrolled pre–post changes not attributable to the intervention. The HB screening-positive rate declined from 100% at baseline to 55.6% at Week 8. Conclusions: Hwa-free demonstrated adequate feasibility, acceptable UX, and preliminary within-group symptom changes. A fully powered randomized controlled trial is warranted.