Treatment of Hidradenitis Suppurativa Evaluation Study (THESEUS): a prospective cohort study.

Background: Hidradenitis suppurativa (HS) is a chronic, painful disease affecting flexures and other skin regions, producing nodules, abscesses and skin tunnels. Laser treatment targeting hair follicles and deroofing of skin tunnels are standard HS interventions in some countries but are rarely offered in the UK.

Objectives: To describe current UK HS management pathways and influencing factors to inform the design of future randomized controlled trials (RCTs).

Methods: THESEUS was a nonrandomized 12-month prospective cohort study set in 10 UK hospitals offering five interventions: oral doxycycline 200 mg daily; oral clindamycin and rifampicin both 300 mg twice daily for 10 weeks, extended for longer in some cases; laser treatment targeting hair follicles; deroofing; and conventional surgery. The primary outcome was the combination of clinician-assessed eligibility and participant hypothetical willingness to receive each intervention. The secondary outcomes were the proportion of participants selecting each intervention as their final treatment option; the proportion who switch treatments; treatment fidelity; and attrition rates. THESEUS was prospectively registered on the ISRCTN registry: ISRCTN69985145.

Results: The recruitment target of 150 participants was met after 18 months, in July 2021, with two pauses due to the COVID-19 pandemic. Baseline demographics reflected the HS secondary care population: average age 36 years, 81% female, 20% non-White, 64% current or ex-smokers, 86% body mass index ≥ 25, 68% with moderate disease, 19% with severe disease and 13% with mild disease. Laser was the intervention with the highest proportion (69%) of participants eligible and willing to receive treatment, then deroofing (58%), conventional surgery (54%), clindamycin and rifampicin (44%), and doxycycline (37%). Laser was ranked first choice by the greatest proportion of participants (41%). Attrition rates were 11% and 17% after 3 and 6 months, respectively. Concordance with doxycycline was 52% after 3 months due to lack of efficacy, participant choice and adverse effects. Delays with procedural interventions were common, with only 43% and 26% of participants starting laser and deroofing, respectively, after 3 months. Uptake of conventional surgery was too small to characterize the intervention. Switching treatment was uncommon and there were no serious adverse events.

Conclusions: THESEUS has established laser treatment and deroofing for HS in the UK and demonstrated their popularity with patients and clinicians for future RCTs.