Validation of the Korean version of the Clinical Opiate Withdrawal Scale

The use of prescription opioids has risen dramatically in South Korea in recent years; however, there is no standardized Korean-language instrument to assess opioid withdrawal. The Clinical Opiate Withdrawal Scale (COWS) is a widely used clinician-rated measure for assessing the severity of opioid withdrawal. We aimed to validate the Korean version of the COWS (K-COWS) among patients receiving opioid therapy.

We translated and culturally adapted the 11-item COWS into Korean. A total of 66 adult patients with opioid use disorder who were experiencing withdrawal symptoms were assessed. Each patient was evaluated using the K-COWS and completed the Subjective Opiate Withdrawal Scale (SOWS), the brief 3-item Opioid Craving Scale (OCS-3), and the single-item Opioid Craving Visual Analog Scale (OC-VAS). We examined the internal consistency, factor structure [through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA)], and convergent/discriminant validity of the K-COWS.

The K-COWS showed good internal consistency (Cronbach's α = 0.79; 95% CI = 0.71-0.86). EFA supported a two-factor structure (physical vs. autonomic clusters) that explained 39% of the variance. In CFA, the two-factor model showed a marginally acceptable fit (χ²  = 47.76, CFI = 0.915, RMSEA = 0.082), whereas the unidimensional alternative showed a poor fit. The K-COWS strongly correlated with the SOWS (r = 0.74, 95% CI = 0.61-0.83, p < 0.001), indicating good convergent validity for withdrawal. In contrast, correlations with the craving measures were weak (OCS-3: r = 0.19, p > 0.05; OC-VAS: r = 0.20, p > 0.05), supporting discriminant validity.

The K-COWS is reliable and has demonstrated construct validity for withdrawal severity in Korean clinical settings. Given the preliminary nature of the factor structure, the total score is recommended for clinical decision-making. Future studies should assess inter-rater reliability and confirm the structure in larger, more diverse samples.