Axial spondyloarthritis can be ‘reliably diagnosed’ shortly after chronic back pain onset
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Key takeaways:
- Among patients diagnosed with definite axial SpA at baseline, 94% retained the diagnosis 2 years later.
- Features most associated with axial SpA at 2 years were HLA-B27 positivity and sacroiliitis on imaging.
Most patients with recent-onset chronic back pain suspected of axial spondyloarthritis can be “unequivocally and reliably diagnosed” at their first rheumatology visit, according to data published in the Annals of the Rheumatic Diseases.
“In axial spondyloarthritis (axSpA), despite substantial advances in diagnostic process and treatment, diagnostic delays remain a challenge,” Mary L. Marques, MD, of Leiden University Medical Center in the Netherlands, and colleagues wrote. “A timely diagnosis is still hard to achieve, with mean worldwide diagnostic delays of about 7 years, which is markedly longer than for other chronic inflammatory rheumatic and musculoskeletal diseases.
“Recently, the Assessment of Spondyloarthritis International Society (ASAS) developed quality standards to improve health care for patients with axSpA, stressing the need of immediate referral to a rheumatologist of patients suspected of having axSpA,” they added. “However, there is clear paucity of data showing that rheumatologists are indeed capable of reliably diagnosing axSpA shortly after symptom onset.”
To assess how many patients with recent-onset chronic back pain retain a diagnosis of axial SpA 2 years after referral to a rheumatologist, and examine the accuracy of baseline axial SpA diagnoses after 2 years, Marques and colleagues analyzed data from the Spondyloarthritis Caught Early — or SPACE — cohort. According to the researchers, SPACE is a European inception cohort that includes patients with chronic back pain of unknown origin beginning between 3 months and 2 years before baseline.
The final analysis included 552 patients with a mean symptom duration of 13 months. Each patient was classified based on the level of confidence of their diagnosis — ranging from definite axial SpA to definite non-axSpA — at baseline and 2 years later. The primary outcome was a clinical diagnosis of axial SpA at 2 years.
At baseline, 32% of patients were diagnosed with definite axial SpA, according to the researchers. Among these patients with definite axial SpA, 94% retained a high-confidence diagnosis after 2 years. Among patients not diagnosed with definite axial SpA at baseline, only 8% retained a definite diagnosis after 2 years, suggesting only “modest” benefit of repeated assessments, the researchers wrote.
Uncertainty remained in 30% of patients at 2 years, being classified as neither definite axial SpA nor non-axial SpA.
According to the researchers, the features that best distinguished those who had or did not have definite axial SpA after 2 years were HLA-B27 positivity and sacroiliitis on imaging. After 2 years, HLA-B27 positivity was 81% in the definite axial SpA group vs. 12% in the definite non-axial SpA group. In addition, sacroiliitis at baseline “was completely absent” on imaging for patients with definite non-axial SpA at 2 years.
“Patients with recent onset [chronic back pain] suspected of axSpA referred to the rheumatologist can be unequivocally and reliably diagnosed already at their first presentation to a rheumatologist,” Marques and colleagues wrote. “Diagnostic judgements remained relatively stable over time, with nearly one-third of the referred patients having [definite axial SpA] after 2 [years].
“This is the first study formally proving that patients with axSpA can be diagnosed by rheumatologists shortly after symptom onset,” they added. “Our data support the ASAS recommendation of immediate referral of patients with ‘suspicion of axSpA’ to a rheumatologist.”
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