Supplementary Material for: Could Residents Adequately Assess the Severity of Hidradenitis Suppurativa? Interrater and Intrarater Reliability Assessment of Major Scoring Systems

A wide variety of assessment tools have been proposed for hidradenitis suppurativa (HS) until now, but none of them meets the criteria for an ideal score. Because there is no gold standard scoring system, the choice of the measure instrument depends on the purpose of use and even on the physician’s experience in the subject of HS. The aim of this study was to assess the intrarater and interrater reliability of 6 scoring systems commonly used for grading severity of HS: the Hurley Staging System, the Refined Hurley Staging, the Hidradenitis Suppurativa Severity Score System (IHS4), the Hidradenitis Suppurativa Severity Index (HSSI), the Sartorius Hidradenitis Suppurativa Score and the Hidradenitis Suppurativa Physician’s Global Assessment Scale (HS-PGA). On the scoring day, 9 HS patients underwent a physical examination and disease severity assessment by a group of 16 dermatology residents using all evaluated instruments. Then, intrarater reliability was calculated using intraclass correlation coefficient (ICC), and interrater variability was evaluated using the coefficient of variation (CV). In all 6 scorings the ICCs were >0.75, indicating high intrarater reliability of all presented scales. The study has also demonstrated moderate agreement between raters in most of the evaluated measure instruments. The most reproducible methods, according to CVs, seem to be the Hurley staging, IHS4, and HSSI. None of the 6 evaluated scoring systems showed a significant advantage over the other when comparing ICCs, and all the instruments seem to be very reliable methods. The interrater reliability was usually good, but the most repeatable results between researchers were obtained for the easiest scales, including Hurley scoring, IHS4 and HSSI.