Table 1.
Key outcome measures in common use for assessment of axial disease in ankylosing spondylitis
| Outcome | Instrument | Main components | Reference |
|---|---|---|---|
| Disease activity | BASDAI | Self-administered VAS questionnaire: fatigue, axial pain, peripheral joint pain, tenderness, stiffness | [99] |
| ASAS 20, 40, 70 | Percentage improvement in three out of four domains: patient global, pain, function and inflammation | [100,101] | |
| ASAS 5/6 | > 20% improvement in all four ASAS domains + one of CRP or metrology | [101] | |
| Partial remission | < 20% activity in all four ASAS domains | [100] | |
| ASDAS | Includes CRP | [102] | |
| Physical function | BASFI | Self-administered VAS questionnaire: 10 questions about day-to-day tasks | [103] |
| Dougados index | Self-administered VAS questionnaire: 20 questions about day-to-day tasks | [104] | |
| HAQ-S | Self-administered questionnaire scoring difficulty of 25 day-to-day tasks | [105] | |
| Metrology | BASMI | Five clinical measurements: cervical rotation, tragus to wall distance, lateral lumbar flexion, modified Schober's, intermalleolar distance | [106] |
| EDASMI | Four clinical measurements: cervical rotation, lateral lumbar flexion, chest expansion, and internal rotation of the hip | [107] | |
| Spine X-ray score | mSASSS | Disease of anterior vertebral corners on a lateral cervical and lumbar radiograph | [108] |
| Spine MRI score | Berlin Score | Vertebral junction disease by quantifying bone marrow oedema | [109] |
| ASspiMRI-a | Vertebral junction disease by quantifying bone marrow oedema and erosions | [110] | |
| SPARCC Index | Vertebral junction disease by quantifying bone marrow oedema | [111] | |
| Work | AS-WIS | A simple 20-item questionnaire to measure work instability in AS | [112] |
| WPAI-SHP | Quantitative measure of reduced productivity, both at work and during nonwork activities | [113] | |
| Questionnaire | |||
| Health-related quality of life | ASQoL | Addresses symptoms, function and disease-related concern | [114] |
| SF-36 | Physical and mental health assessment | [115] |
AS, ankylosing spondylitis; ASAS, Assessment of Spondyloarthritis International Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; ASQoL, Ankylosing Spondylitis Quality of Life; ASspiMRI, Ankylosing Spondylitis Spine MRI score; AS-WIS, Ankylosing Spondylitis Work Instability Scale; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Functional Index; CRP, C-reactive protein; EDASMI, Edmonton Ankylosing Spondylitis Metrology Index; HAQ, Health Assessment Questionnaire; MRI, magnetic resonance imaging; mSASSS, Modified Stoke Ankylosing Spondylitis Spinal Score; SF-36, Short-form 36; SPARCC, Spondyloarthritis Research Consortium of Canada; VAS, visual analogue scale; WPAI-SHP, Work Productivity and Activity Impairment-Specific Health Problem Questionnaire.