1. A Core Domain Set For Hidradenitis Suppurativa Trial Outcomes: An International Delphi Process
L. Thorlacius*1,2, J. R. Ingram*3, B. Villumsen4, S. Esmann1, J. S. Kirby5, A. B. Gottlieb6, J. F. Merola7,
R. Dellavalle8, S. M. Nielsen2, R. Christensen2, Amit Garg‡9, G. B. E. Jemec‡1 on behalf of the
HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC)
1) Department of Dermatology, Zealand University Hospital, Roskilde; Health Sciences Faculty, University of
Copenhagen, Denmark
2) Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
3) Institute of Infection & Immunity, Cardiff University, University Hospital of Wales, Heath Park, Cardiff, UK
4) The Patients' Association HS Denmark, Denmark
5) Department of Dermatology, Penn State Hershey Medical Center, Hershey, USA
6) Department of Dermatology, New York Medical College, Valhalla NY, USA
7) Harvard Medical School, Boston, Massachusetts, USA; Department of Dermatology and Department of Medicine,
Division of Rheumatology, Brigham and Women's Hospital, Boston, Massachusetts, USA
8) Dermatology Service, US Department of Veteran Affairs Medical Centre, Denver, USA
9) Department of Dermatology, Hofstra Northwell School of Medicine, New Hyde Park, New York, USA
* The first two authors share co-first authorship
‡The last two authors share co-senior authorship
British Journal of Dermatology. DOI: /bjd.16672

2. DEPARTMENT OF DERMATOLOGY, ZEALAND UNIVERSITY HOSPTIAL, DENMARK
HISTORIC
An international steering group consisting of researchers, clinicians and a patient research partner under the HISTORIC initiative has been formed to guide the development of the COS.
The steering group consists of nine members; a patient research partner who is a board member of The HS Patients' Association in Denmark, two dermatologists with expertise in both HS research and clinical work; four dermatologists with a special interest in outcome measures in dermatology; a biostatistician from OMERACT experienced in COS development and a MD Ph.D. student.

3. Introduction What’s already known?
Outcome measure instruments used for hidradenitis suppurativa are markedly heterogeneous, with 30 instruments recently found in 12 randomised trials.
Lack of consensus regarding outcome measure instruments limits evidence synthesis and increases the risk of outcome reporting bias.
A core domain set is an agreed minimum set that should be measured and reported in all clinical trials for a specific condition

4. Objective
To achieve global multi-stakeholder consensus on a Core Outcome Set (COS) of domains regarding what to measure in clinical trials for HS.

5. Methods An international Delphi consensus project
Using a multi-stakeholder approach, involving patients and healthcare professionals (HCPs) including dermatologists, surgeons, HS nurses, the pharmaceutical industry and medical regulators.
Aiming to have a 1:1 ratio of patients:HCPs
Patients were identified from patient associations and via dermatologists with a special interest in HS
The meeting locations were planned for both Europe and North America to ensure that patient and HCP opinions from both continents were incorporated

6. Methods Phase 1: Identification of candidate items
Systematic literature review
Qualitative data from patient interviews and focus group studies
Conducted in both Denmark and North America
Interviews were conducted until the point of saturation (meaning, no new constructs or ideas are added)
Survey of healthcare professionals
Participants were asked to list all areas of importance regarding HS, related to any aspect of the disease or treatment of the disease

7. Methods Phase 2: Consensus process
HS stakeholders participated in a Delphi process which included five anonymous e-Delphi rounds and four face-to-face consensus meetings to reach consensus on the final COS
The combined list of potential items identified in Phase 1 were scored
(1-3 = not important, 4-6 = important but not critical or 7-9 = critical)
Items were discussed, rescored and then linked into over-arching domains and rediscussed
Items were then included in COS or excluded, based on consensus opinion

8. DEPARTMENT OF DERMATOLOGY, ROSKILDE HOSPTIAL, DENMARK
Phase 1
Phase 2

9. Patient global , Physician global Flare frequency and duration,
Results
Pain
Physical Signs
Anatomic location, Surface area, Total lesion count, Inflammatory lesion count, Number of abscesses, Number of inflamed nodules, Number of sinus tracts,
Number of fistulae
HS specific QOL
Physical functioning, Psychological functioning, Psychosocial functioning, Emotional well-being, Ability to work or study
Global assessment
Patient global , Physician global
Progression of course
Flare frequency and duration,
Time to recurrence
Inner ring: the core set
Domains and items that reached ‘consensus in’ for patients and HCPs
Outer ring:
Items that did not reach ‘consensus in’ but were marked as a specific research agenda or important in specific trials at consensus meetings
Symptoms
Biomarkers
Time to heal
Middle ring:
Domains and items that reached ‘consensus in’ for patients or HCPs

10. Discussion
The HISTORIC initiative has begun the process to develop a Core Outcome Set (COS) for HS trials
The final core domain set includes five domains:
pain
physical signs
hidradenitis suppurativa-specific quality of life
global assessment
progression of course
A sixth domain, symptoms, was highly supported by patients and not by healthcare professionals; it was recommended for inclusion in the COS by the HISTORIC Steering Committee as an additional domain, given the importance of patient-reported domains

11. Conclusions What does this study add?
Our study provides global multi-stakeholder consensus on core outcome domains for hidradenitis suppurativa
The implementation of a COS for HS clinical trials should improve the interpretation and comparison of future studies testing interventions for HS and reduce the risk of outcome reporting bias and heterogeneity across studies
After achieving consensus on what to measure in HS clinical trials, the next step for the HISTORIC initiative will be to reach consensus on the outcome measurement instruments best suited to measure each of the core domains in the COS

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