Treatment of hidradenitis suppurativa evaluation study: the THESEUS prospective cohort study

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 ...