Severity and Area Score for Hidradenitis (SASH): a novel outcome measurement for hidradenitis suppurativa.

This novel scale is a reliable and valid HS outcome instrument and may capture a wide range of patients by assessing BSA. Future research is necessary to demonstrate its responsiveness. What's already known about this topic? The major HS disease activity scales rely on lesions counts and have moderate-to-good reliability. Body surface area (BSA) is one of the physical signs included in the Core Outcome Set for HS, but is not a part of existing HS disease activity scales. What does this study add? A novel disease severity scale, the Severity and Area Score for Hidradenitis (SASH), was developed and the psychometric properties assessed. There was high inter-rater reliability of 0·75 and 0·76 when BSA was scored on an ordinal scale, and an excellent intrarater reliability of 0·98. The SASH score also demonstrated convergent validity with extant instruments. What are the clinical implications of this work? The ability of clinicians to accurately assess disease status will be improved. Implementation of the SASH score will help guide and assess the effectiveness of appropriate treatment choice.