Response shift due to diagnosis and primary treatment of localized prostate cancer: a then-test and a vignette study

Whether a prostate cancer diagnosis induces response shift has not been established so far. Therefore, we assessed response shift in men who were diagnosed with localized prostate cancer. Out of 3,892 men who completed a questionnaire before screening, 82 were subsequently diagnosed with prostate cancer. Response shift was assessed in 52 (response 63%) by the then-test (EuroQol self-rating of health, Short-Form 36 mental health and vitality) and a novel method: rating of vignettes relating to side effects of prostate cancer treatment (urinary, bowel and erectile dysfunction). Three then-tests were conducted: two referencing pre-diagnosis (measured pre- and post-treatment), and one referencing pre-treatment (measured post-treatment). Then-test scores of pre-diagnosis health were significantly higher than original scores, indicating a more positive judgement in retrospect. Then-test scores of pre-treatment health were lower than original scores. Especially the vignette on erectile dysfunction was rated less bad after diagnosis versus before (P < 0.001, moderate effect size). We found evidence for response shift in men who were diagnosed with prostate cancer. Men evaluated urinary, bowel, and erectile dysfunction as less bad after they had become patients who can expect to experience these side effects. The rating of vignettes is a promising additional technique to assess response shift.