Abstract

Defining the minimal clinically meaningful improvement (MCMI) is crucial to understanding the treatment effects on health-status measures. We estimated the MCMI on the quality of erection questionnaire (QEQ), a validated measure specific to assess erectile quality during sexual intercourse. Data were from two controlled trials of an investigational phosphodiesterase type 5 inhibitor. Improvement on the Erectile Function domain of the International Index of Erectile Function was used as the anchor. For men who improved by exactly 1 erectile dysfunction severity category (anchor group (n=95)), clinically meaningful improvement (CMI, estimated with mean QEQ total change score from baseline to end of treatment) and MCMI (estimated with the lower limit of the 95% confidence interval of the mean) were 22.4 (s.d., 2.2) and 18.0 points, respectively. For the difference between the anchor group and men with no change in severity category (n=116), CMI and MCMI were 17.7 (s.d., 2.9) and 12 points, respectively. Distribution-based analyses (baseline s.e. of measurement (s.e.m.)=7.99, end-of-treatment s.e.m.=8.22 and s.e. of difference=11.46) supported a proposed MCMI of 12 points. Convergence of anchor-based and distribution-based criteria supports at least a 12-point difference in QEQ scores between treatments as clinically important.