Validation study of the Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 for patients with testicular cancer.

OBJECTIVE

To validate the Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 in Japanese-speaking testicular cancer survivors.

METHODS

A total of 200 testicular cancer survivors were recruited at eight high-volume institutions in Japan. The participants completed the Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26, the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 and the International Index of Erectile Function 15 questionnaires. A total of 40 participants completed a retest of the questionnaires 2 weeks after the first response. The psychometric properties of the Japanese version including test-retest reliability, internal consistency and concurrent validity were evaluated.

RESULTS

The mean age at response was 43 years (range 22-74 years), and the mean period after treatment was 77 months (range 0-416 months). The response rate for each item, except sexual function, was high, and the percentage of missing values was less than 3.5%. For test-retest reliability, seven of 12 scales met the criteria (intraclass correlation 0.70-0.86). For internal consistency, four of seven scales met the criteria (Cronbach's alpha 0.62-0.91). For concurrent validity, treatment side effects of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 were related to some domains of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30. The sex-related subscales of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 were moderately correlated with some International Index of Erectile Function 15 domains.

CONCLUSIONS

The psychometric properties of the Japanese version are equivalent to the properties of the original European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26. The Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 questionnaire is a useful tool to assess the health-related quality of life of testicular cancer patients.