Objective: The Radiumhemmets Scale of Disease-Specific Symptom Assessment-Prostate Cancer has been used in several studies. However, no test-retest reliability study of it has been conducted concerning the assessment of urinary, anal sphincter or large bowel function. The aim of this study was to evaluate the reliability of items assessing these functions.
Material and methods: We investigated 89 prostate cancer patients randomly selected from a group of patients diagnosed in Stockholm. The patients answered 24 questions assessing anal sphincter, large bowel and urinary function twice, with a 3-week interval in-between, to assess reliability.
Results: Most of the questions assessing bowel and urinary symptoms showed substantial or near-perfect agreement. The kappa value for bowel symptom items was > or = 0.60 for all items, except for defecation urgency (0.40-0.55). The kappa value for urinary symptom items varied between 0.43 and 1.0, except for urinary urgency (0.30-0.39).
Conclusions: When comparing the impact of different symptoms of anal sphincter, large bowel or urinary tract dysfunction, it may be important to consider that defecation urgency and urinary urgency have the highest measuring error (low reliability). This error dilutes assessed associations with, for example, decreased quality of life. Nevertheless, the test-retest reliability for anal sphincter, large bowel and urinary symptoms indicates that surveys yield meaningful information.