Defining criteria used to evaluate response to treatment of acne vulgaris.

Results from controlled studies form the basis of overall perceptions regarding the efficacy and safety of specific treatments. In acne vulgaris, determining statistical significance related to mean percentage reduction in inflammatory and noninflammatory lesion counts, investigator global assessment, and patient (subject) global assessment have formed the basis of most studies. Results may be impacted by several mitigating factors related to inclusion and exclusion criteria and variations in study "power." Recently, standards for evaluation of response to acne treatment have been reconsidered, with new methodologies suggested throughout the approval process. For example, the standard of "complete clearance" has been introduced. How the new methodologies compare with previous standards, and how new criteria will impact the reporting and interpretation of trial results are reviewed in this article. Specific study outcomes, including those reported in more recent trials with topical adapalene, are utilized as illustrative examples.