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 retrospectiv e recall of prediagnostic disease-targeted function among men diagnosed wit h prostate cancer. METHODS. A convenience sample of 133 prostate cancer cases were administere d a baseline questionnaire shortly after diagnosis that asked about prediag nostic urinary, sexual, and bowel function. They were surveyed again concer ning the same items 6 months later and asked to recall their prediagnostic function. Reports of prediagnostic function obtained at baseline and 6 mont hs are compared, as are measures of change derived from these reports. Perc ent agreement and weighted kappas are calculated to measure the extent of a greement. RESULTS. Over 70% of the men reported prediagnostic functioning at the high est level on 12 of 17 survey items. For each of these items, recall at 6 mo nths was identical to the baseline survey response for greater than or equa l to 69% of the men. The values of the weighted kappas for changes computed with baseline reports (prospective) and changes computed with 6-month reca ll (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, an d 0.692 for sexual function. CONCLUSIONS. At baseline, men recently diagnosed with prostate cancer repor t few disease-related problems before diagnosis, and a high percentage of m en recall this accurately 6 months later. There is reasonably high agreemen t between baseline and 6-month estimates of prediagnostic function and betw een prospective and retrospective measures of change over 6 months.