Psychometric evaluation of the Korean version of the Child Oral Health Impact Profile Short Form (COHIP-SF 19): a cross-sectional study

BACKGROUND: The Child Oral Health Impact Profile Short Form 19 (COHIP-SF 19) is widely used to assess oral health-related quality of life (OHRQoL). However, its psychometric properties have not been evaluated in Korea. This study aimed to examine the factor structure of the Korean COHIP-SF 19 and to assess its reliability and validity in schoolchildren. METHODS: Data were obtained from 980 fourth-grade elementary school students (aged 10 years) participating in a 2023 national oral health program. Children completed the COHIP-SF 19 online, and clinical examinations recorded caries, malocclusion, gingivitis, and oral hygiene status. Exploratory and confirmatory factor analyses were performed. Reliability was assessed using Cronbach's alpha, corrected item-total correlations, and test-retest intraclass correlation coefficients (ICC). Convergent and discriminant validity were evaluated using self-rated oral health, perceived treatment need, and clinical findings. RESULTS: Exploratory factor analysis supported a four-factor solution with separation of the self-image subscale. Confirmatory factor analysis showed better fit for the modified model than the original structure. The total score demonstrated excellent test-retest reliability (ICC = 0.905). Cronbach's alpha for the 19 items was 0.729, with higher values in the modified model. Convergent validity was confirmed by correlations with self-rated oral health and treatment need. Discriminant validity was supported: children with caries or malocclusion had lower scores, whereas gingivitis and oral hygiene showed no associations. Gender differences appeared only in the modified model, with girls reporting lower functional well-being and social well-being scores. CONCLUSIONS: The Korean COHIP-SF 19 demonstrated satisfactory psychometric properties in 10-year-old schoolchildren. The modified model showed improved structural validity, higher internal consistency, and better subgroup discrimination, including by gender. These findings support its use in clinical and epidemiological research.