App-Based ACT Intervention Shows Preliminary Benefit for Hwa-byung Symptoms

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medRxiv Published April 23, 2026 Medically reviewed April 24, 2026 Study authors: Kwon, C.-Y.; Lee, B.; Kim, M.; Mun, J.-h.; Seo, M.-G.; Yoon, D. DOI ↗ By Dr. Ji-eun Park, MD · Brain, Mind & Pain

Key Takeaway

Consider that an app-based ACT intervention shows preliminary promise for Hwa-byung, but results are limited by lack of a control group.

This pilot feasibility trial evaluated a 4-week app-based acceptance and commitment therapy (ACT) intervention (Hwa-free) in 30 adults aged 19-80 years diagnosed with Hwa-byung. The study had no control group. Primary outcomes focused on user experience (UX) via a 22-item survey at Week 4; secondary outcomes included HB-related symptom scales, depression, anxiety, anger expression, psychological flexibility, health-related quality of life, and heart rate variability. Follow-up occurred at baseline, Week 2, Week 4, and Week 8.

Adherence was 71.2% over 28 days (mean app use 19.9 ± 7.9 days). Positive UX response rates exceeded 80% for video content (82.8-89.7%), HB self-assessment (86.2%), meditation therapy (86.2%), and in-app guidance (85.7%). Pre-post improvements from baseline to Week 4 were observed: HB Symptom Scale (delta = -9.8, Cohen's d = -0.92), Beck Depression Inventory-II (delta = -13.3, d = -1.11), and State Anger (delta = -7.8, d = -0.96). The HB screening-positive rate declined from 100% at baseline to 55.6% at Week 8. Overall, 11 of 18 clinical scales showed improvement.

Adverse events were infrequent and unrelated to the intervention; 2 participants discontinued (30 enrolled, 28 modified intention-to-treat). Tolerability was acceptable based on UX. Key limitations include the pilot design, lack of a control group, and the need for a future randomized controlled trial. Funding and conflicts were not reported.

For clinicians, these preliminary findings suggest that a digital ACT intervention may offer clinically meaningful improvements in Hwa-byung-related symptoms, but causal conclusions cannot be drawn due to the uncontrolled design. Further research is warranted.

Study Details

Study typeRct

EvidenceLevel 2

PublishedApr 2026

View Original Abstract ↓

Background: Hwa-byung (HB) is a Korean culture-bound syndrome characterised 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 effect of an acceptance and commitment therapy (ACT)-based DTx application, Hwa-free, for HB. Methods: Adults aged 19-80 years diagnosed with HB were enrolled in a four-week app-based intervention with assessment at baseline (Week 0), Week 2, Week 4, and Week 8 follow-up. The primary outcome was UX assessed via a 22-item survey at Week 4. Secondary outcomes included HB-related symptom and personality scales, depression, anxiety, anger expression, psychological flexibility, health-related quality of life, and heart rate variability. Results: Of 45 screened, 30 were enrolled and 28 constituted the modified intention-to-treat population. Mean app use was 19.9 +/- 7.9 days (71.2% adherence over 28 days). Adverse events were infrequent and unrelated to the intervention. Positive response rates exceeded 80% for video content (items 2-4: 82.8-89.7%), HB self-assessment (86.2%), meditation therapy (86.2%), and in-app guidance (85.7%). Pre-post improvements from baseline to Week 4 were observed in 11 of 18 clinical scales, including HB Symptom Scale (delta = -9.8, Cohen's d = -0.92), Beck Depression Inventory-II (delta = -13.3, d = -1.11), and state anger (delta = -7.8, d = -0.96). 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 evidence of clinically meaningful improvement in HB-related symptoms. Future randomised controlled trial is warranted.