The translation and validation of the Japanese version of the patient assessment of constipation quality of life scale
The aim of the present study was to conduct a psychometric evaluation of the patient assessment of constipation quality of life scale (PAC-QOL) in the Japanese language. The PAC-QOL was translated into Japanese. After being linguistically validated, the Japanese version of the PAC-QOL was administered to a sample of 121 patients. Validation studies were conducted to evaluate the internal consistency reliability (Cronbach’s alpha), reproducibility [intraclass correlation coefficients (ICCs)], the convergent validity (correlated with the Short-Forum 36 Health Survey), the discriminant validity [correlated with the constipation scoring system (CSS)], the cross-sectional validity (analysis of variance models), and responsiveness (effect size) of the PAC-QOL scales. The internal consistency was good for all of the scales (Cronbach’s alpha coefficient >0.7) and reproducible (ICCs >0.7). The four scales of the PAC-QOL were significantly correlated with the Short-Forum 36 Health Survey (P < 0.01 except for the satisfaction subscale) and the CSS scores (P < 0.01 except for the satisfaction subscale). The PAC-QOL scale scores were significantly associated with constipation severity (P < 0.05). The effect size in patients reporting improvements in constipation over the treatment period was moderate to large, with a subscale effect size ranging from 0.69 to 1.18 and an overall scale effect size of 1.12. Similar findings were observed in the original validation study. The linguistic and psychometric evaluation demonstrated the validity of the Japanese version of the PAC-QOL.