Characterization of Patients With Ankylosing Spondylitis and Nonradiographic Axial Spondyloarthritis in the US‐Based Corrona Registry

OBJECTIVE: To describe the characteristics of patients with ankylosing spondylitis (AS) and patients with nonradiographic axial spondyloarthritis (SpA) in the US. METHODS: Demographics, clinical characteristics, patient‐reported outcomes, and treatment characteristics of patients with AS and those with nonradiographic axial SpA were assessed at the time of enrollment in the Corrona Psoriatic Arthritis/Spondyloarthritis Registry. Patients with AS were defined as those who fulfilled the 1984 modified New York criteria for AS; patients with nonradiographic axial SpA were defined as all other patients with axial SpA who did not fulfill the radiology criterion. RESULTS: Of the 407 patients with a diagnosis of axial SpA who were included in this study, 310 had AS, and 97 had nonradiographic axial SpA. Although patients with nonradiographic axial SpA were younger and showed a trend toward a shorter symptom duration, the nonradiographic axial SpA and AS groups shared a similar disease burden, as reflected by comparisons of disease activity and function, quality of life, pain, fatigue, job absenteeism, and loss of work productivity (all P > 0.05). The proportions of patients with nonradiographic axial SpA and patients with AS who received prior biologic disease‐modifying drugs (DMARDs) (74.2% and 64.8%, respectively) or were currently receiving biologic DMARDs (63.9% and 61.3%, respectively) were also similar (P > 0.05). CONCLUSION: This was the first nationwide study to characterize patients with AS and nonradiographic axial SpA in the US. Consistent with studies published outside of the US, this study showed that patients with nonradiographic axial SpA and patients with AS shared a comparable degree of disease burden and had similar treatment patterns in clinical practice.