Reliability and responsiveness of a prostate cancer questionnaire for radiotherapy-induced side effects

Few self-assessment cancer-specific questionnaires/modules have yet been developed for radiotherapy-induced side effects. The aim of the present study was to test the reliability and responsiveness of a prostate cancer (PC)-specific questionnaire. Thirty-one patients with PC graded their urinary and intestinal symptoms and their sexual function on the questionnaire. A doctor and a nurse performed a structured interview and graded the patient's symptoms with the same questions. The procedure was performed at both the start and the end of the treatment. A high concordance regarding symptom detection was seen between the patient, nurse and the doctor. The inter-rater test shows intraclass correlation coefficient (ICC) values above 0.60 in all scales. The internal reliability exceeded the lower limit (Cronbach a >0.70) for all scales. The test-retest gave acceptable reliability for all scales (ICC > or = 0.60). All scales indicated increased problems during radiotherapy. The questionnaire was proven to be valid for the evaluations of urinary and intestinal problems and for sexual function in PC patients.