This international study validated and finalized the ASAS classification criteria for axial spondyloarthritis. It tested candidate criteria in 649 chronic back pain patients across 25 centres. The goal was to create criteria that capture early, non-radiographic disease using MRI, not just plain films.
When you see a young adult with chronic back pain, the age cutoff matters: these criteria only apply if symptoms began before age 45 and have lasted over 3 months.
The key conceptual shift is that you no longer need radiographic sacroiliitis to classify axial SpA. MRI-detected active sacroiliitis, meaning bone marrow oedema suggestive of SpA, satisfies the imaging arm years before plain films change.
Think of the two arms as complementary rule-in pathways. The imaging arm is highly specific (97.3%), so a positive MRI plus one feature nearly confirms disease. The clinical arm rescues patients without imaging findings by anchoring on HLA-B27 plus two features.
This paper formalized non-radiographic axial SpA, which enabled trials of TNF blockers in patients before irreversible structural damage. Remember these are classification criteria validated in a 60% prevalence referral setting, and performance in low-prevalence primary care is unproven.
This international study validated and finalized the ASAS classification criteria for axial spondyloarthritis. It tested candidate criteria in 649 chronic back pain patients across 25 centres. The goal was to create criteria that capture early, non-radiographic disease using MRI, not just plain films.
When you see a young adult with chronic back pain, the age cutoff matters: these criteria only apply if symptoms began before age 45 and have lasted over 3 months.
The key conceptual shift is that you no longer need radiographic sacroiliitis to classify axial SpA. MRI-detected active sacroiliitis, meaning bone marrow oedema suggestive of SpA, satisfies the imaging arm years before plain films change.
Think of the two arms as complementary rule-in pathways. The imaging arm is highly specific (97.3%), so a positive MRI plus one feature nearly confirms disease. The clinical arm rescues patients without imaging findings by anchoring on HLA-B27 plus two features.
This paper formalized non-radiographic axial SpA, which enabled trials of TNF blockers in patients before irreversible structural damage. Remember these are classification criteria validated in a 60% prevalence referral setting, and performance in low-prevalence primary care is unproven.