Assessing health-related quality of life in young Japanese children with chronic conditions: Preliminary validation of the DISABKIDS smiley measure

BACKGROUND Although there is an increasing need to investigate the health-related quality of life (HRQOL) of children and adolescents with chronic conditions in Japan, there is currently no standardized measure in which young children can directly answer questions about their HRQOL. The DISABKIDS Smiley measure uses face emoticons to measure HRQOL and distress caused by illness and related treatments among young children. We tested the reliability and validity of the DISABKIDS Smiley measure in a sample of young Japanese children. METHODS After translating the child and parent questionnaires into Japanese, a pre-test was performed to test the content validity in accordance with guidelines from the DISABKIDS Group. In total, 60 child-parent pairs were recruited to participate in the survey. We measured internal consistency of the scales using Cronbach's alpha as well as Guttman split-half, test-retest reliability using intraclass correlation coefficients (ICCs) at a two-week interval, and ICCs between child- and parent-reported scores. Convergent validity of the scale was also examined against the Kiddy-KINDL scale. RESULTS Both child-reported and parent-reported scales showed good internal consistency and split-half reliability. Test-retest reliability of the child-reported version (ICC = 0.53, p = 0.004) was lower than that of the parent-reported version (ICC = 0.80, p < 0.001). Moderate to good agreement between child- and parent- reported scales was observed in both the first (ICC = 0.75, p < 0.001) and second administration (ICC = 0.71, p < 0.001). Moderate to very strong positive correlations were observed with the total score of the Kiddy-KINDL child-reported version (r = 0.51, p < 0.001), and facets of the Kiddy-KINDL parent-reported version (ranging from r = 0.364 to r = 0.60, p < 0.001) and total score (r = 0.71, p < 0.001). CONCLUSIONS The psychometric property of the instrument showed that the Japanese version of the DISABKIDS Smiley can be applied to assess the HRQOL of Japanese children with chronic conditions. Further investigation will be needed to explore the reliability and validity for repeated use of the instrument in clinical practice as an indicator of clinical significance.