Treatment of Hidradenitis Suppurativa Evaluation Study: the THESEUS prospective cohort study
Authors: Ingram John R , Bates Janine , Cannings-John Rebecca , Collier Fiona , Gibbons Angela , Harris Ceri , Hood Kerenza , Howells Laura , Howes Rachel , Leighton Paul , Riaz Muhammad , Rodrigues Jeremy , Stanton Helen , Thomas Kim S , Thomas-Jones Emma 
Published: December 2023

Background
Hidradenitis suppurativa is a chronic inflammatory skin disease characterised by recurrent inflammatory lesions and skin tunnels in flexural sites such as the axilla. Deroofing of skin tunnels and laser treatment are standard hidradenitis suppurativa interventions in some countries but not yet introduced in the United Kingdom.

Objective
To understand current hidradenitis suppurativa management pathways and what influences treatment choices to inform the design of future randomised controlled trials.

Design
Prospective 12-month observational cohort study, including five treatment options, with nested qualitative interviews and an end-of-study consensus workshop.

Setting
Ten United Kingdom hospitals with recruitment led by dermatology and plastic surgery departments.

Participants
Adults with active hidradenitis suppurativa of any severity not adequately controlled by current treatment.

Interventions
Oral doxycycline 200 mg once daily; oral clindamycin and rifampicin, both 300 mg twice daily for 10 weeks initially; laser treatment targeting the hair follicle (neodymium-doped yttrium aluminium garnet or alexandrite); deroofing; and conventional surgery.

Main outcome measures
Primary outcome was the proportion of participants who are eligible, and hypothetically willing, to use the different treatment options. Secondary outcomes included proportion of participants choosing each of the study interventions, with reasons for their choices; proportion of participants who switched treatments; treatment fidelity; loss to follow-up rates over 12 months; and efficacy outcome estimates to inform outcome measure instrument responsiveness.

Results
Between February 2020 and July 2021, 151 participants were recruited, with two pauses due to the COVID-19 pandemic. Follow-up rates were 89% and 83% after 3 and 6 months, decreasing to 70% and 44% at 9 and 12 months, respectively, because pandemic recruitment delays prevented all participants reaching their final review. Baseline demographics included an average age of 36 years, 81% female, 20% black, Asian or Caribbean, 64% current or ex-smokers and 86% with a raised body mass index. Some 69% had moderate disease, 19% severe disease and 13% mild disease.
Regarding the study’s primary outcome, laser treatment was the intervention with the highest proportion (69%) of participants who were eligible and hypothetically willing to receive treatment, followed by deroofing (58%), conventional surgery (54%), the combination of oral clindamycin and rifampicin (44%) and doxycycline (37%). Considering participant willingness in isolation, laser was ranked first choice by the greatest proportion (41%) of participants. The cohort study and qualitative study demonstrated that participant willingness to receive treatment was strongly influenced by their clinician.
Fidelity to oral doxycycline was only 52% after 3 months due to lack of effectiveness, participant preference and adverse effects. Delays receiving procedural interventions were common, with only 43% and 26% of participants commencing laser therapy and deroofing, respectively, after 3 months. Treatment switching was uncommon and there were no serious adverse events.
Daily pain score text messages were initiated in 110 participants. Daily responses reduced over time with greatest concordance during the first 14 days.

Limitations
It was not possible to characterise conventional surgery due to a low number of participants.

Conclusion
The Treatment of Hidradenitis Suppurativa Evaluation Study established deroofing and laser treatment for hidradenitis suppurativa in the United Kingdom and developed a network of 10 sites for subsequent hidradenitis suppurativa randomised controlled trials.

Future work
The consensus workshop prioritised laser treatment and deroofing as interventions for future randomised controlled trials, in some cases combined with drug treatment.

Trial registration
This trial is registered as ISRCTN69985145.

Funding
This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 12/35/64) and is published in full in Health Technology Assessment; Vol. 27, No. 30. See the NIHR Funding and Awards website for further award information.