Assessment of inter-rater reliability of clinical hidradenitis suppurativa outcome measures using ultrasonography.

Background: Hidradenitis suppurativa (HS) staging and severity is typically based upon physical examination findings, which can result in misclassification of severity based on subclinical disease activity and significant variation between healthcare providers. Ultrasonography (US) is an objective tool to help evaluate subclinical disease and to more accurately classify disease severity.

Aim: To evaluate inter-rater reliability in HS disease severity assessment using clinical and US techniques.

Methods: In total, 20 subjects underwent clinical evaluation of HS, independently by two physicians, using clinical outcome measures, including Hurley, Sartorius, HS Physician Global Assessment (HS-PGA) and Hidradenitis Suppurativa Clinical Response (HiSCR). US was subsequently performed, and clinical assessments were repeated. Intraclass correlation coefficients (ICC) were obtained to evaluate inter-rater agreement of each outcome measure before and after US.

Results: Pre-US to post-US improvement in ICC was seen with the Sartorius, HiSCR nodule and abscess count, and the HiSCR draining fistula count. The scores went from having 'good' rater agreement for Sartorius and HiSCR nodule and abscess count, to 'poor' rater agreement for HiSCR draining fistula count, to 'excellent' rater agreement among these scores.

Conclusion: US improved inter-rater agreement and should be used in conjunction with physical examination findings to evaluate disease severity to ensure uniform staging of HS.