Minimal clinically important differences in the erectile function domain of the
International Index of Erectile Function scale.
Author(s): Rosen RC, Allen KR, Ni X, Araujo AB.
Affiliation(s): New England Research Institutes, Inc., Watertown, MA 02472, USA.
rrosen@neriscience.com
Publication date & source: 2011, Eur Urol. , 60(5):1010-6
BACKGROUND: Despite widespread adoption of the six-item erectile function (EF)
domain of the International Index of Erectile Function (IIEF) as a clinical trial
end point, there are currently no objective data on what constitutes a minimal
clinically important difference (MCID) in the EF domain.
OBJECTIVE: Estimate the MCID for the IIEF EF domain.
DESIGN, SETTING, AND PARTICIPANTS: Anchor-based MCIDs were estimated using data
from 17 randomized, double-blind, placebo-controlled, parallel-group clinical
trials of the phosphodiesterase type 5 inhibitor (PDE5-I) tadalafil for 3345
patients treated for 12 wk.
MEASUREMENTS: The anchor for the MCID is the minimal improvement measure
calculated using change from baseline to 12 wk on IIEF question 7: "Over the past
4 weeks, when you attempted sexual intercourse how often was it satisfactory for
you?" MCIDs were developed using analysis of variance (ANOVA)- 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).
RESULTS AND LIMITATIONS: The ROC-based MCID for the EF domain was 4, with
estimated sensitivity and specificity of 0.74 and 0.73, respectively. MCIDs
varied significantly (p<0.0001) according to baseline ED severity (mild: 2;
moderate: 5; severe: 7). MCIDs consistently distinguished between patients in the
validation sample classified as no change or minimally improved overall and by
geographic region, ED etiology, and age group. MCIDs did not differ by age group,
geographic region, or ED etiology. Current analyses were based on 17 clinical
trials of tadalafil. Results need to be replicated in studies using other PDE5-Is
or in nonpharmacologic intervention studies.
CONCLUSIONS: The contextualization of treatment-related changes in terms of
clinically relevant improvement is essential to understanding treatment efficacy,
to interpreting results across studies, and to managing patients effectively.
This analysis provides, for the first time, anchor-based estimates of MCIDs in
the EF domain score of the IIEF.
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