Intra-rater agreement of lesion counts in hidradenitis suppurativa

The heterogeneous presentation of hidradenitis suppurativa (HS) lesions can result in variation in clinical trial outcome assessments when performed by the same rater as well as different raters. In the PIONEER I and II trials of patients with HS, there was substantial disagreement between repeated lesion counts by the same rater during a time period in which little true change is expected. Standardization of lesion classification and improved rater training are critical for advancing HS drug development.