External Validation of the IHS4-55 in a European Antibiotic-Treated Hidradenitis Suppurativa Cohort

Kelsey R. Van Straalen*, Thrasyvoulos Tzellos, Afsaneh Alavi, Farida Benhadou, Carlos Cuenca-Barrales, Mathilde Daxhelet, Mathieu Daoud, Ourania Efthymiou, Evangelos J. Giamarellos-Bourboulis, Philippe Guillem, Wayne Gulliver, Gregor B.E. Jemec, Alexander Katoulis, Anke Koenig, Elizabeth Lazaridou, Michelle A. Lowes, Angelo V. Marzano, Lukasz Matusiak, Alejandro Molina-Leyva, Chiara MoltrasioAndreas Pinter, Concetta Potenza, Errol P. Prens, Jorge Romaní, Ditte M. Saunte, Christopher Sayed, Nevena Skroza, Dimitra Stergianou, Jacek C. Szepietowski, Anastasia Trigoni, Eva Vilarrasa, Athanassios Kyrgidis, Christos C. Zouboulis, Hessel H. Van Der Zee

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)


Background: Previously, a new dichotomous outcome was developed, calculated as 55% reduction in the International Hidradenitis Suppurativa 4 (IHS4-55) score. It was validated in datasets of adalimumab and placebo-treated HS patients. External validation is an important aspect of clinical outcomes. Objectives: We aimed to externally validate the novel dichotomous IHS4-55 in a non-biologic treated dataset of HS patients. Methods: Data from a previously published European-wide prospective clinical study of antibiotic treatment of HS patients were used to assess the association of IHS4-55 achievement with individual reduction in inflammatory nodules, abscesses, and draining tunnels. Moreover, the associations between IHS4-55 positivity and achievement of the minimal clinically important differences (MCIDs) for Dermatology Life Quality Index (DLQI), Numerical Rating Scale (NRS) Pain, and NRS Pruritus were analyzed. Results: Data were obtained from 283 individual patients, of which 36.4% (103/283) were treated with clindamycin and rifampicin and 63.6% (180/283) with tetracyclines for 12 weeks. Achievers of the IHS4-55 demonstrated a significant reduction the counts of inflammatory nodules, abscesses, and draining tunnels (all p < 0.001). Additionally, IHS4-55 achievers had an odds ratio for achieving the MCID of DLQI, NRS Pain, and NRS Pruritus of 2.16 (95% CI 1.28-3.65, p < 0.01), 1.79 (95% CI 1.10-2.91, p < 0.05), and 1.95 (95% CI 1.18-3.22, p < 0.01), respectively. Conclusions: This study shows the external validity of the novel IHS4-55 by demonstrating a significant association between IHS4-55 achievement and a reduction in inflammatory lesion counts as well as achievement of MCIDs for DLQI, NRS Pain, and NRS Pruritus in an antibiotic-treated cohort. These findings support the use of the IHS4-55 as a novel primary outcome measure in clinical trials.

Original languageEnglish
Pages (from-to)362-367
Number of pages6
Issue number3
Publication statusPublished - 13 Jun 2023

Bibliographical note

Funding Sources
The publication fees of this article were overtaken by the EHSF e.V

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© 2023 Authors. All rights reserved.


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