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The Treatment of Hidradenitis Suppurativa Evaluation Study (THESEUS) will provide vital information to answer questions that were identified as priority areas for research by patients with the condition and the doctors and nurses who treat them.


Light and laser treatment for Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a long term, painful skin condition that affects approximately 1% of adults. It involves boils in areas such as the armpits and groins. It affects young adults of working age. HS has a big effect on quality of life due to pain, scarring and release of pus. It also affects sex and relationships.

Study videos

The following videos are for educational and informational use only, and have been prepared to give greater insight and background to patients and the public, and healthcare professionals with an interest in current approaches to Hidradenitis suppurativa.

Please note these videos contain scenes of surgical procedures.

For patients and public

Deroofing of sinus tracts in Hidradenitis Suppurativa for Patients and Public

For healthcare professionals

Deroofing of sinus tracts in Hidradenitis Suppurativa for Healthcare Professionals

Study aims

To inform the design of future HS trials and to understand how HS treatments are currently used.

This involves five steps:

  1. Describe the treatments used around the country (like the dose of medicines, type of operations used);
  2. See whether patients and doctors might consider joining a clinical trial in the future;
  3. Define how patients with HS are currently managed within the health service. Learn what influences patients’ and clinicians’ treatment choices;
  4. Select the best ways of measuring response to treatment (outcome measures);
  5. Ask patients and doctors to agree the best design for future HS trials.

Design and methods

We have designed this study in response to the funders who requested a trial for “Management of HS”. Our team includes people with HS and the leader of a patients’ support group, skin doctors, GPs, surgeons and research experts. We are supported by a Clinical Trials Unit to make sure that the research is high quality. We are backed by two networks that coordinate research by skin doctors and plastic surgery doctors around the country.

We have already run surveys of people with HS, skin doctors and surgeons about HS treatment. From these surveys, we have picked five main treatments for further study.

We will invite people with HS to join the study. By inviting people who are treated by skin doctors and those treated by surgeons, we should receive information about a range of treatment options. The volunteers will be able to pick from the range of treatments available locally and, for the year after, we will record what happens to them. We will measure how well the treatment has worked using recommended questionnaires and will help to interpret the questionnaire results by checking what changes in score matter to patients. We will also ask some of the study participants to talk to us in more detail about their involvement in the study so that we can understand how to make it easier for people to take part in future studies like this one. During the study we will video record the surgical and laser operations to make a training video for future trials and to ensure a consistent approach to delivering the surgical operations.

Outcome measures

The HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC) was formed as a collaboration between the International Dermatology Outcome Measures (IDEOM) initiative, the Cochrane Skin - Core Outcome Set Initiative (CS-COUSIN) and Zealand University Hospital, Roskilde. The first HISTORIC goal was to develop a core set of outcome domains that are relevant to patients and clinicians. HISTORIC has now moved on to considering which instruments to recommend in order to measure each domain in all future clinical trials.

Patient and public involvement

The President of the HS Trust has been a member of our bid team from the beginning and will be part of the group that manages the study. She led our patient survey, using the HS Trust website and social media. The survey, completed by 358 people, helped to shape our study plan. Throughout our study, we will interview participants about their study experiences. We will ask about reasons why they might, or might not, take part in future studies. A group of people with HS and doctors/nurses/ researchers involved in the study will use the information gathered during this study to agree the best designs for future HS research.


We will present the findings from our study at international meetings of doctors and researchers. We will publish them openly in journals, ensuring that access to the articles is free to everyone. The HS Trust patient support group will host links to these publications on its website, including a plain language summary and podcasts. We will also send a summary of the research results to everyone who takes part in the study.

Hidradenitis Suppurativa Trust

THESEUS is supported by the HS Trust, a UK Registered Charity dedicated to the raising of awareness of HS.

General enquiries

Please contact