Comparison of Two Methods for Assessing Erectile Function Before Radical Prostatectomy

Patient-reported outcome instruments for erectile function often ask respondents about their experience over the previous 4wk. This is problematic for baseline assessment of patients with prostate cancer (PC) before treatment, as the previous 4wk would probably have involved procedures such as biopsy and considerable anxiety related to their diagnosis. At San Raffaele Hospital, the International Index of Erectile Function (IIEF-6) was used to ask new PC patients about function in both the previous 4wk and 6mo. We compared responses to these two timeframes. IIEF-6 scores were lower for the 4-wk period (median 24 vs 26; p<0.0001) predominately because approximately one in six of patients with good function in the 6-mo time frame had very poor function in the 4wk before completing the questionnaire (adequate erectile function 60% and 51%; absolute difference 9%, 95% confidence interval 8-10%). Results were further confirmed using a comparison group of 5395 patients with PC newly diagnosed at Memorial Sloan Kettering Cancer Center who had similar function in the previous 6mo. Erectile function evaluation for men presenting with PC should involve asking about typical function over a 6-mo period rather than focusing on the previous 4wk. PATIENT SUMMARY: Questionnaires to assess erectile function often ask men about function in the previous 4wk. We found that this underestimates function in new prostate cancer patients and that such men should be asked about typical function over a 6-mo period.