Measuring outcomes in ankylosing spondylitis: pearls and pitfalls.

PURPOSE OF REVIEW: Patients with ankylosing spondylitis (AS) warrant a comprehensive clinical assessment because of the lack of biomarkers of disease activity, prognosis and response to biologic therapy. Multiple AS-related questionnaires have been developed to assess the disease status accurately, but feasibility remains a problem in clinical practice. The purpose of this review is to assess the pearls and pitfalls of AS-related outcome measures.

RECENT FINDINGS: Single-item questionnaires to measure pain, stiffness and fatigue in patients with AS are easily administrable but may lack a sufficient degree of responsiveness on an individual patient level. The Bath Ankylosing Disease Activity Index remains the gold standard for assessing disease activity in a routine practice, despite poor correlation with C-reactive protein (CRP) levels and MRI inflammation. The Ankylosing Spondylitis Disease Activity Score, a validated and highly discriminatory tool for assessing disease activity in AS, has been developed but lacks feasibility as erythrocytic sedimentation rate and CRP values are often not available during a clinic visit. RAPID-3 appears feasible to assess patients with AS quantitatively over time in busy clinical settings.

SUMMARY: The assessment of disease status in AS is complex and is impacted by multiple factors. The biggest challenge in AS is to incorporate the disease-specific indices into a routine practice. VIDEO ABSTRACT: http://links.lww.com/COR/A42.