Summary Background Monitoring disease activity over time is a prerequisite for clinical practice and research. Valid and reliable outcome measurement instruments (OMIs) and staging systems provide researchers and clinicians with benchmark tools to assess the primary and secondary outcomes of interventional trials and to guide treatment selection properly. Objectives To investigate inter‐rater reliability and agreement in instruments currently used in hidradenitis suppurativa (HS), with dermatologists experienced in HS as the rater population of interest. Methods In a prospective completely balanced design, 24 patients with HS underwent a physical examination by 12 raters (288 assessments) using nine instruments. The results were analysed using generalized linear mixed models. Results For the staging systems, the study found good inter‐rater reliability for Hurley staging in the axillae and gluteal region, moderate inter‐rater reliability for Hurley staging in the groin and for Physician's Global Assessment, and fair inter‐rater reliability for refined Hurley staging and the International HS Severity Scoring System. For all the tested OMIs, the observed intervals for limits of agreement were very wide relative to the ranges of the scales. Conclusions The very wide intervals for limits of agreement imply that substantial changes are needed in clinical research in order to rule out measurement error. The results illustrate a difficulty, even for experienced HS experts, to agree on the type and number of lesions when evaluating disease severity. The apparent caveats call for global efforts, such as the HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC) to reach consensus on how best to measure physical signs of HS reliably in randomized trials. What's already known about this topic? Without valid and reliable instruments to measure outcomes, researchers and clinicians lack the necessary benchmarks to assess primary and secondary end points of interventional trials properly. Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease. Several outcome measure instruments exist for HS, but their validation is generally incomplete or of relatively low methodological quality. What does this study add? Using a prospective completely balanced design this study examined inter‐rater reliability with HS‐experienced dermatologists as the rater population of interest. The study did not find very good reliability for any included instrument or lesion counts. This study illustrates the difficulty in finding agreement on the type and number of HS lesions, even among experts. The results question whether physical signs are best measured by a traditional physician lesion count instrument. What are the clinical implications of this work? For staging, Hurley staging and physician global visual analogue scale proved to be acceptable instruments in terms of inter‐rater reliability. For the instruments designed to measure changes in health status, our study illustrates how difficult ...

This paper is organized jointly by the European Academy of Dermatology and Venereology (EADV) Task Force (TF) on Quality of Life (QoL) and Patient‐Oriented Outcomes and the EADV TF on acne, rosacea and hidradenitis suppurativa (ARHS). The purpose of this paper was to present current knowledge about QoL assessment in HS, including data on HS‐specific health‐related (HR) QoL instruments and HRQoL changes in clinical trials, and to make practical recommendations concerning the assessment of QoL in people with HS. HS results in significant quimp that is higher than in most other chronic skin diseases. HS impact in published studies was assessed predominantly (84% of studies) by the Dermatology Life Quality Index (DLQI). There is a lack of high‐quality clinical trials in HS patients where HRQoL instruments have been used as outcome measures. One double‐blind randomized placebo‐controlled trial on infliximab with low number of participants reported significantly better HRQoL improvement in the treatment group than in the placebo group. Well‐designed clinical studies in HS patients to compare different treatment methods, including surgical methods and assessing long‐term effects, are needed. Because of lack of sufficient validation, the Task Forces are not at present able to recommend existing HS‐specific HRQoL instruments for use in clinical studies. The EADV TFs recommend the dermatology‐specific DLQI questionnaire for use in HS patients. The EADV TFs encourage the further development, validation and use of other HS‐specific, dermatology‐specific and generic instruments but such use should be based on the principles presented in the previous publications of the EADV TF on QoL and Patient‐Oriented Outcomes.

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Summary Background Hidradenitis suppurativa (HS), also referred to as acne inversa, is a debilitating skin disease characterized by inflammatory nodules, chronic abscesses and tunnels (fistulae and sinuses). The association with pilonidal sinus disease (PSD) is frequently reported but not well documented. Objectives To determine the prevalence and characteristics of inflammatory skin lesions located in the intergluteal fold (IGF) of patients with HS. Methods This was an international multicentre retrospective cross‐sectional study based on data collection from a large cohort of patients with HS with and without histopathology. Results From a total of 2465 patients with HS included in the study, 661 (27%) reported lesions in the IGF. These patients were significantly more often smokers and had more severe HS. Of the 238 patients with an available clinical diagnosis, intergluteal‐HS (IG‐HS) was diagnosed in 52 patients (22%) and PSD was diagnosed in 186 patients (78%). IG‐HS was associated with the localization of HS in the proximity of the IGF, including the buttocks, genitals and the anus. There was a possibility of misclassification bias in this study as a clinical/image‐based diagnosis or histopathology of the IGF lesions was not always available. Conclusions The high prevalence of PSD suggests a strong link between both entities. Therefore, it may be useful to identify common pathophysiological mechanisms and develop common therapeutic strategies. What's already known about this topic? The occurrence of pilonidal sinus disease has not been clearly reported among patients with hidradenitis suppurativa/acne inversa. What does this study add? This is the first study that investigated the prevalence of pilonidal sinus disease among a large cohort of patients and identified the patient characteristics. Risk factors that might help to improve the management of patients were identified.

SummaryBackgroundBiologics targeting inflammatory mediators can achieve clinical improvements in hidradenitis suppurativa (HS). However, their clinical efficacy shows great interpatient variability in daily practice.ObjectivesTo investigate the anti‐inflammatory potency of a selection of currently available biologics and prednisolone for the treatment of HS in an ex vivo skin culture system using lesional HS biopsies.MethodsLesional skin samples from 10 patients with HS and skin samples from five healthy controls were cultured ex vivo and exposed to prednisolone or biologics targeting tumour necrosis factor (TNF)‐α, interleukin (IL)‐17A, IL‐12/23p40 or CD20 (adalimumab, infliximab, secukinumab, ustekinumab and rituximab, respectively). Real‐time quantitative polymerase chain reaction and cytokine bead arrays were used to measure the inhibitory effect of the biologics on cytokines and antimicrobial peptides (AMPs).ResultsThe relative mRNA expression of all tested cytokines and AMPs was significantly downregulated by all anti‐inflammatory agents (P < 0·001). The protein production of the proinflammatory cytokines TNF‐α, interferon γ, IL‐1β, IL‐6 and IL‐17A was significantly inhibited by adalimumab, infliximab, ustekinumab, prednisolone (all P < 0·001) and rituximab (P = 0·0071), but not by secukinumab (P = 0·0663). On both mRNA and protein levels, adalimumab, infliximab and prednisolone reduced the levels of a broader mix of individual cytokines than secukinumab, ustekinumab and rituximab. Moreover, a significant inhibitory effect on mRNA expression levels of inflammatory markers in healthy control skin was observed only for TNF‐α inhibitors (P < 0·001) and prednisolone (P = 0·0015).ConclusionsThis ex vivo study suggests that TNF‐α inhibitors and prednisolone are the most powerful inhibitors of proinflammatory cytokines and AMPs in HS lesional skin, which concurs with our clinical experience in patients with HS.

SummaryHidradenitis suppurativa (HS) is an uncommon skin condition that causes painful swollen red bumps in the folds of the body (underarms, under breasts, groin, and buttocks). It can be mistaken for bacterial abscess or boils, but HS is not caused by bacteria. HS occurs in about 0.1-1% people in the US and Europe. The authors include people with HS, dermatologists, surgeons, members of the pharmaceutical industry and medical regulators from 13 countries and four continents. This study aimed to find out what clinical trials for HS should measure, such as symptoms (e.g. pain, itch), physical changes (e.g. skin redness or swelling), or impact on people's lives (e.g. quality of life). To do this, the study included two groups: people with HS and healthcare providers (physicians, pharmaceutical industry representatives, and regulatory representatives) and conducted in-person meetings with presentations and discussions as well as surveys to gather opinions on which measures to include. The result of the meetings, discussions, and surveys showed that at least 70% of the people with HS and healthcare providers recommended that clinical trials include measures of: (1) physical changes due to HS (e.g. redness); (2) changes in the course of HS (e.g. flare-ups); (3) quality of life changes due to HS specifically; (4) satisfaction (e.g. satisfaction with treatment) ; (5) pain; (6) other symptoms (e.g. itching); and a global rating (i.e. overall rating, considering everything, of the severity of the condition). This work is important because it included many different types of people who contribute to HS treatment, including the people who have HS, develop or regulate treatments, and treat people with HS. More work is coming, and it will focus on final suggestions on what to measure and how to measure it in trials treating HS.

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Background: Validated, inclusive and easy-to-use outcomes for hidradenitis suppurativa are essential both in the clinical trial setting and clinical practice. The continuous IHS4 is a validated tool that dynamically assesses nodules/abscesses/draining tunnels and classifies disease severity as mild/moderate/severe. However, dichotomous outcomes are often required for clinical trials reporting.Objective: To develop and validate a dichotomous outcome based on IHS4 that can be used in clinical trial settings and day-to-day clinical practice.Methods: De-identified data from the PIONEER-I and -II studies were accessed through Vivli. Potential IHS4 thresholds were analysed using baseline to Week 12 data from adalimumab-and placebo-treated hidradenitis suppurativa patients in the PIONEER-I trial. The final threshold was chosen based on its ability to discriminate between patients treated with adalimumab or placebo and its association with