Summary Background Clinical trials require valid and reliable outcome measures to facilitate the interpretation and communication of results, and the secondary use of data for systematic reviews. There are numerous tools available to assess the severity of acne vulgaris in clinical trials, and extensive debate about the merits of these.
Objectives To review the literature about investigator-assessed outcome measures used in clinical trials for acne vulgaris; and to evaluate the measurement properties of these tools.
Methods A systematic literature review was conducted of articles outlining and evaluating investigator-assessed outcome measures for acne.
Results Thirty-one papers met the criteria for inclusion in the literature review, including nine papers proposing a novel means of assessing acne, and five evaluating existing outcome measures. Variable attempts had been made to evaluate these tools.
Conclusions The array of evaluation tools used in acne trials prohibits good secondary analysis of trial data, and complicates the interpretation of study results, potentially compromising clinical care. Existing outcome measures need to be assessed further and agreement reached about which should be used more widely. Other innovative methods of assessing acne should also be explored.