Translation and validation of EORTC QLQ-C30 into Indonesian version for cancer patients in Indonesia.

OBJECTIVE Quality of life studies in Indonesia are still uncommon. This research was aimed to validate the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 in Indonesian version. The standard procedure of forward-backward translation was adhered to in the translation procedures. The validity procedure included reliability, convergent and discriminant validity, known-groups validity, factor analysis and external convergent validity. METHODS Data were collected from cancer patients in the Oncology Department of Sardjito Hospital, Yogyakarta, Indonesia, who were treated with cisplatin at the dosage ≥50 mg/m(2) as monotherapy or in combinations. The Short Form-36 was used to assess the external convergent validity of our translated questionnaire. RESULTS One hundred and twenty-eight patients were recruited from March 2009 to November 2009. The internal consistency with values of >0.70 was observed in the Indonesian version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 scales. All items in the questionnaire met the criteria of convergent and discriminant validity, except for items 5. Both of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 and the Short Form-36 showed that different diagnoses were associated with a similar impact on quality of life. Factor analysis showed that only the role function and social function loaded onto the second factor together. Correlations between the Indonesian versions of both questionnaires were moderate: between 0.18 and 0.48 for the physical, emotional, social, fatigue and pain domains. CONCLUSIONS The Indonesian version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 can be used as a questionnaire to assess quality of life in Indonesian cancer patients with high-emetogenic treatments.