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 stu dy was to test the reliability and responsiveness of a prostate cancer (PC) specific questionnaire. Thirty-one patients with PC graded their urinary an d intestinal symptoms and their sexual function on the questionnaire. A doc tor and a nurse performed a structured interview and graded the patient's s ymptoms with the same questions. The procedure was performed at both the st art and the end of the treatment. A high concordance regarding symptom dete ction was seen between the patient, nurse and the doctor. The inter-rater t est shows intraclass correlation coefficient (ICC) values above 0.60 in all scales. The internal reliability exceeded the lower limit (Cronbach alpha > 0.70) for all scales. The test-retest gave acceptable reliability for all scales (ICC greater than or equal to 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.