In a research project, investigators want to study the course of the disease of axial spondylitis: the causes of disease onset, prognosis, and treatment effects. The goal is to improve treatment and in the long run also prevention of the disease. The project has a focus on the body's own substance prostaglandin, and its proinflammatory role in spondylitis, but also other substances may be analyzed in blood and urine samples.

The purpose of the research project is include newly diagnosed treatment-naive patients with axial spondyloarthritis, to follow them after 1 and 2 years after treatment start, to collect clinical data, questionnaires, blood and urinsamples to find blood or urine markers that can be used for precision therapy of axial spondylitis.

The EISPA study is an epidemiological and translational study in axial spondylitis patients who are included in the Swedish Rheumatology Quality Register (SRQ). EISPA aims to include consecutive newly diagnosed axial spondylitis patients.

Despite the fact that the disease is relatively common, it takes on average 10 years after start of symptoms for patients be diagnosed with axial spondylitis.

Axial spondylitis diagnosis is based on clinical findings rather than diagnostic tests, which reflects lack of knowledge about what causes the disease. At present, our possibilities to predict the course of the disease (and thereby individualize the care of the patient) are limited. Current treatment decreases inflammation rather than treating the cause of the disease.

The first treatment step of axial spondylitis is with non-steroidal anti-inflammatory drugs or COX inhibitors, which usually have insufficient effect against inflammatory pain and stiffness. In addition, these drugs are associated with side effects, such as gastrointestinal and cardiovascular side effects. Axial spondylitis is a multifactorial disease where the arachidonic acid cascade, an increased prostaglandin production and release may play a major role. With this there is a clear potential to develop new specific drugs to slow down the prostaglandin cascade in patients with axial spondylitis.

Inclusion Criteria:

• newly diagnosed patients with axial spondyloarthritis
• treatment-naive
• 18 years of age or older
• Swedish-speaking
• Able to give informed consent

Exclusion Criteria:

• DMARD treatment,
• ongoing infection
• ongoing malignancy

Consecutive newly diagnosed adult patients with axial spondyloarthritis who are treatment-naïve, speak Swedish, and do not have an ongoing malignancy or infection. Patients need to be able to give an informed consent.

Investigators include 20 anonymised blood samples of blood donors for comparison of prostaglandin levels.