Table 1

 Specification (definition of the terms)

*The expert is a physician, usually a rheumatologist, with expertise in inflammatory back pain and the use of biological agents. Expert should be locally defined.
†The expert should consider clinical features (history and examination), serum acute phase reactant levels and/or imaging results, such as radiographs demonstrating rapid progression or MRI indicating ongoing inflammation.
‡Sulfasalazine: treatment for at least four months at standard target dose or maximally tolerated dose unless contraindicated or not tolerated. Treatment for less than four months, where treatment was withdrawn because of intolerance or toxicity or contraindicated.
BASDAI, Bath ankylosing spondylitis disease activity index; BASFI, Bath ankylosing spondylitis functional index; CRP, C reactive protein; DMARD, disease modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; NSAID, non-steroidal anti-inflammatory drug; VAS, visual analogue scale (all VAS can be replaced by a numerical rating scale (NRS)).
Diagnosis • Patients normally fulfilling modified New York criteria for definitive ankylosing spondylitis
• Modified New York criteria 19844
  – Radiological criterion: Sacroiliitis, grade ⩾II bilaterally or grade III to IV unilaterally
  – Clinical criteria (two of the following three): low back pain and stiffness for more than three months which improves with exercise but is not relieved by rest; limitation of motion of the lumbar spine in both the sagittal and frontal planes; limitation of chest expansion relative to normal values correlated for age and sex
Active disease • Active disease for ⩾4 weeks
• BASDAI ⩾ 4 (0–10) and an expert* opinion†
Treatment failure • All patients should have had adequate therapeutic trials of at least two NSAIDs. An adequate therapeutic trial is defined as:
  – Treatment for at least 3 months at maximum recommended or tolerated anti-inflammatory dose unless contraindicated
  – Treatment for <3 months where treatment was withdrawn because of intolerance, toxicity, or contraindications
• Patients with pure axial manifestations do not have to take DMARDs before anti-TNF treatment can be started
• Patients with symptomatic peripheral arthritis should have an insufficient response to at least one local corticosteroid injection if appropriate
• Patients with persistent peripheral arthritis must have had a therapeutic trial of sulfasalazine‡
• Patients with symptomatic enthesitis must have failed appropriate local treatment
Contraindications • Women who are pregnant or breast feeding; effective contraception must be practised
• Active infection
• Patients at high risk of infection including:
  – Chronic leg ulcer
  – Previous tuberculosis (note: please follow local recommendations for prevention or treatment)
  – Septic arthritis of a native joint within the past 12 months
  – Sepsis of a prosthetic joint within the past 12 months, or indefinitely if the joint remains in situ
  – Persistent or recurrent chest infections
  – Indwelling urinary catheter
• History of lupus or multiple sclerosis
• Malignancy or pre-malignancy states excluding:
  – Basal cell carcinoma
  – Malignancies diagnosed and treated more than 10 years previously (where the probability of total cure is very high)
ASAS core set for daily practice • Physical function (BASFI or Dougados functional index)
• Pain (VAS, past week, spine at night, from ankylosing spondylitis and VAS, past week, spine, from ankylosing spondylitis)
• Spinal mobility (chest expansion and modified Schober and occiput to wall distance and lateral lumbar flexion)
• Patient’s global assessment (VAS, past week)
• Stiffness (duration of morning stiffness, spine, past week)
• Peripheral joints and entheses (number of swollen joints (44 joints count), enthesitis score such as developed in Maastricht, Berlin, or San Francisco)
• Acute phase reactants (ESR or CRP)
• Fatigue (VAS)
BASDAI • VAS overall level of fatigue/tiredness, past week
• VAS overall level of ankylosing spondylitis neck, back, or hip pain, past week
• VAS overall level of pain/swelling in joints other than neck, back or hips, past week
• VAS overall discomfort from any areas tender to touch or pressure, past week
• VAS overall level of morning stiffness from time of awakening, past week
• Duration and intensity (VAS) of morning stiffness from time of awakening (up to 120 minutes)
Responder criteria • BASDAI: 50% relative change or absolute change of 20 mm (on a scale between 0 and 100) and expert opinion in favour of continuation
Time of evaluation • Between 6 and 12 weeks