Clinically important difference on the Erectile Dysfunction Inventory of Treatment Satisfaction questionnaire in patients with erectile dysfunction

Aim: To determine what constitutes a clinically important difference (CID) on the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS), an 11-item validated questionnaire assessing treatment satisfaction used in clinical trials for patients with erectile dysfunction (ED). Methods: Erectile Dysfunction Inventory of Treatment Satisfaction data were evaluated from a double-blind, fixed-dose trial of 279 men aged 18-6-5 years with ED who were treated with sildenafil 50 or 100 mg or placebo. The primary anchor measure was the erectile function (EF) domain of the International Index of Erectile Function (IIEF), which has a 4-point minimal CID. The CID on the EDITS index score was determined using a regression analysis comparing EDITS and IIEF EF scores at the end of the 8-week treatment. A similar analysis was performed for EDITS and the Erection Hardness Score (EHS) instrument, a single-item questionnaire measuring hardness, which was used as a secondary anchor measure. Results: Erectile Dysfunction Inventory of Treatment Satisfaction and IIEF EF domain scores were highly correlated (Pearson correlation coefficient = 0.75). EDITS total scores across treatments at week 8 averaged (mean +/- standard deviation [SD]) 67.5 +/- 21.6 (range, 0-100; higher scores indicate greater treatment satisfaction); IIEF EF domain scores averaged 22.2 +/- 6.9 (range, 1-30; higher scores indicate higher erectile functioning). The calculated CID for EDITS scores was 9.5 (95% CI, 8.5-10.4; 0.44 SD units), corresponding to a medium effect size. EDITS and EHS instrument scores also correlated highly (Pearson correlation coefficient = 0.64). Placebo-adjusted EDITS mean scores were more than twice the CID, at 23 (95% CI, 17-28) and 28 (95% CI, 23-33) for the 50- and 100-mg doses, respectively. Conclusion: Approximately 10 points on the EDITS index score is considered a CID. Serving as a benchmark, this finding aids interpretation of the clinical relevance of a difference in mean EDITS index scores between treatments for patients with ED.