Validation study of retrospective recall of disease-targeted function: results from the prostate cancer outcomes study.

OBJECTIVES: This was an ancillary methodological study within the Prostate Cancer Outcomes Study (PCOS) to assess the validity of 6-month retrospective recall of prediagnostic disease-targeted function among men diagnosed with prostate cancer.
METHODS: A convenience sample of 133 prostate cancer cases were administered a baseline questionnaire shortly after diagnosis that asked about prediagnostic urinary, sexual, and bowel function. They were surveyed again concerning the same items 6 months later and asked to recall their prediagnostic function. Reports of prediagnostic function obtained at baseline and 6 months are compared, as are measures of change derived from these reports. Percent agreement and weighted kappas are calculated to measure the extent of agreement.
RESULTS: Over 70% of the men reported prediagnostic functioning at the highest level on 12 of 17 survey items. For each of these items, recall at 6 months was identical to the baseline survey response for > or =69% of the men. The values of the weighted kappas for changes computed with baseline reports (prospective) and changes computed with 6-month recall (retrospective) ranged from 0.396 to 0.919 for the 17 individual items. Intraclass correlations for the retrospective versus prospective changes in the multi-item function scores were 0.828 for urinary, 0.618 for bowel, and 0.692 for sexual function.
CONCLUSIONS: At baseline, men recently diagnosed with prostate cancer report few disease-related problems before diagnosis, and a high percentage of men recall this accurately 6 months later. There is reasonably high agreement between baseline and 6-month estimates of prediagnostic function and between prospective and retrospective measures of change over 6 months.