Minimal clinically important differences in the vaginal insertion and successful intercourse items of the sexual...

Despite adoption of the successful vaginal insertion (Q2) and intercourse (Q3) items of the sexual encounter profile (SEP) as end points in clinical trials, there are no objective data on what constitute minimal clinically important differences (MCIDs) in these items.

The objective was to estimate the MCID for SEP Q2 and Q3.

Using data from 17 randomized, controlled trials of the phosphodiesterase type 5 inhibitor tadalafil, we estimated MCIDs for the SEP using anchor-based approaches. The 17 studies included 3,345 patients treated for 12 weeks. The anchor for the MCID is the minimal improvement measure calculated using change from baseline to 12 weeks on the following question: "Over the past 4 weeks, when you attempted sexual intercourse how often was it satisfactory for you?" MCIDs were developed using analysis of variance- and receiver operating characteristic (ROC)-based methods in a subset of studies (N = 11) by comparing patients with and without minimal improvement (N = 863). MCIDs were validated in the remaining six studies (N = 377).

The main outcome measures of this study are SEP Q2 and Q3.

Using the ROC-based approach, the MCID for SEP Q2 was 21.4%, with estimated sensitivity of 0.55 and specificity of 0.73; the MCID for SEP Q3 was 23.0%, with estimated sensitivity of 0.72 and specificity of 0.78. MCIDs for SEP Q2/Q3 varied significantly (P < 0.001) according to baseline erectile dysfunction (ED) severity. MCIDs distinguished between patients in the validation sample classified as no change or minimally improved in each ED etiology, ED duration, and age group, but less well across geographic regions.

The contextualization of treatment-related changes into clinically relevant terms is essential to understanding treatment efficacy, interpreting results across studies, and for effective patient management. Overall, there was a better balance between sensitivity and specificity of the MCIDs using the ROC-based approach for the SEP intercourse success item than for the vaginal insertion item.