Use of an Alternative Method to Evaluate Erythema Severity in a Clinical Trial: Difference in Vehicle Response With Evaluation of Baseline and Postdose Photographs for Effect of Oxymetazoline Cream 1.0% for Persistent Erythema of Rosacea in a Phase 4 Study

Summary

Background

Once‐daily topical oxymetazoline cream 1.0% significantly reduced persistent facial erythema of rosacea in trials requiring live, static patient assessments.

Objective

To critically evaluate the methodology of clinical trials that require live, static patient assessments by determining whether assessment of erythema is different when reference to the baseline photograph is allowed.

Methods

In two identically designed, randomised, phase 3 trials, adults with persistent facial erythema of rosacea applied oxymetazoline or vehicle once daily. This phase 4 study evaluated standardised digital facial photographs from the phase 3 trials to record ≥1‐grade Clinician Erythema Assessment (CEA) improvement at 1, 3, 6, 9, and 12 hours postdose.

Results

Among 835 patients (oxymetazoline n=415, vehicle n=420), significantly greater proportions of patients treated with oxymetazoline versus vehicle (P<0.0001) achieved ≥1‐grade CEA improvement (up to 85.3% vs 29.8%). When reference to baseline photographs was allowed while evaluating posttreatment photographs, the results for oxymetazoline were similar to results of the phase 3 trials, but a significantly lower proportion of vehicle recipients achieved ≥1‐grade CEA improvement (up to 52.3% vs 29.7%; P<0.001). Up to 80.2% of oxymetazoline patients achieved at least moderate erythema improvement, versus up to 22.9% of vehicle patients. The association between patients' satisfaction with facial skin redness and percentage of erythema improvement was statistically significant (Spearman rank correlation, 0.1824; P<0.0001 [oxymetazoline]; 0.0623; P=0.01 [vehicle]).

Conclusions

Assessment of study photographs, with comparison to baseline, confirmed significant erythema reduction with oxymetazoline on the first day of application. Compared to the phase 3 trials results, significantly fewer vehicle recipients attained ≥1‐grade CEA improvement, inferring a mitigated vehicle effect. This methodology may improve the accuracy of clinical trials evaluating erythema severity.

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