BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease affecting up to 2% of European adults. Disease activity is commonly assessed by counting of inflammatory nodules, abscesses and fistulas. Thus, it is time consuming and subject to inter-rater variability. 

OBJECTIVES: To assess HS disease activity by means of automated, digital image analyses. 

METHODS: Digital images of axillary and inguinogenital HS are collected in a clinical routine setting, using smartphones and a CE medical device certified skin imaging platform. Photos are automatically normalized for illumination and color. Image characteristics such as an erythema-score and image complexity are calculated for all photos comparing affected and unaffected skin. Parameters are used to calculate the HS Activity and Severity Score (HiSASS) and correlated with the average Physician Global Assessment (PGA) of each picture provided by 3 independent dermatologists. Follow-up images are used to evaluate disease activity over time. 

This project aims at standardizing disease assessment for HS patients for robust measurements of disease activity and treatment success.