The EORTC quality of life questionnaire QLO-C30 (version 3.0): Validation study for spanish prostate cancer patients

Objective: The EORTC Quality of Life Group has developed a questionnaire for evaluating Quality of Life in international clinical trials: EORTC QLQ-C30, which is widely used in many countries. The purpose of this study was to assess the psychometric properties of the third version of this questionnaire, EORTC QLQ-C30 (version 3.0), when applied to Spanish prostate cancer patients. Methods: A sample of 137 prostate cancer patients prospectively filled in the questionnaire three times: on the first and last day of the treatment, and in the follow-up period. Psychometric evaluation of the structure, reliability and validity was made. Results: Multitrait scaling analysis showed that most item-scale correlation coefficients met the standards of convergent and discriminant validity. Few exceptions appeared mainly in CF. Most scales had low to moderate inter-correlations. Cronbach's coefficients of the scales were above 0.7, except for the CF and NV values. Group comparison analyses showed better QL in patients with higher Performance Status. Changes in functioning and symptom areas appeared throughout the different measurements, which were in line with the treatment process. Conclusions: The EORTC QLQ-C30 (version 3.0) appeared as a reliable and valid instrument when applied to a sample of Spanish prostrate cancer patients. The results are in line with previous studies.