This study is a large national multicenter, longitudinal, prospective follow-up of patients presenting with early inflammatory back pain in order to set up a database to facilitate several investigations on diagnosis, prognosis, epidemiology, pathogenesis and medico-economics in the field of early inflammatory back pain and spondyloarthritis

This large national multicenter, longitudinal, prospective follow-up of patients presenting with early inflammatory back pain in order to set up a database to facilitate several investigations on diagnosis, prognosis, epidemiology, pathogenesis and medico-economics in the field of early inflammatory back pain and spondyloarthritis.

The Patients were recruited if they had inflammatory back pain of more than 3months and less than 3years. Patients will be followed every 6months during the first 2years then every year during at least 5years. Apart from information collected on a Case Report Form (demographics, disease activity, severity, co-morbidities, socio-economics, treatments, radiological and MRI evaluation of the spine and the pelvis according to the local investigators, and for some centers bone densitometry and ultrasonography of entheses), the digital X-rays and MRI of the spine and pelvis are stored using a specific software (Carestream) and the biological samples (DNA, RNA, sera, urines) are centralized at the Biological Resources Center (Bichat Hospital).

This large cohort should facilitate the conduct of researches in different areas (clinical, medico-economics, translational) in order to improve our knowledge on the pathogenesis and natural history of axial spondyloarthritis

Inclusion Criteria:

• Patients aged over 18 and under 50 years
• Inflammatory back pain (buttock, lumbar or thoracic spine) fulfilling either the Calin orBerlin criteria :
• Calin criteria (at least 4 of 5 criteria must be met) (ref. 25):
• Insidious onset
• Onset before age 40
• Persistence since at least three months
• Morning stiffness 30 minutes
• Improvement with exercise
• Berlin criteria (at least 2 of 4 criteria must be met) (ref. 26):
• Morning stiffness 30 minutes
• Improvement with exercise and absence of improvement at rest
• Nocturnal pain in the second part of the night
• Alternating buttock pain
• Symptom duration more than 3 months and less than 3 years
• Symptoms suggestive of spondyloarthritis according to the local investigator's assessment(e.g. score ≥5 on a 0 to 10 numerical rating scale in which 0 = no suggestive and 10 = verysuggestive of spondyloarthritis)
• Realization of a prior medical examination (article L.1121-11 of the Code of the Public health)
• Informed consent Dated and signed voluntarily

Exclusion Criteria:

• Other spinal disease clearly defined (eg symptomatic mechanical discopathy)
• Pregnant woman
• History of alcoholism, drug addiction, psychological problems, severe co-morbidities which might interfere with the validity of the informed consent and/or prevent an optimal compliance of the patient to the cohort
• It was possible to include patients who have received or are receiving a thorough treatment such as Sulfasalazine, Methotrexate or Azathioprine. However any history of treatment with biotherapy including anti-TNF therapy defined exclusion criteria
• Corticosteroid intake was permitted only in case of a dose lower than 10 mg prednisoneper day and stable for at least 4 weeks prior baseline
• MRI contraindication
• No affiliation to the French National Social Security System

Patients presenting early inflammatory back pain of more than 3 months and less than 3 years