Early diagnosis of axial spondyloarthritis among patients with chronic back pain using a clinical screening tool and referral strategy.

Objective: Lack of timely referral of suspected axial spondyloarthritis (axSpA) patients to rheumatologists is an important modifiable reason for diagnostic delay of axSpA. We assessed the usefulness of a self-referral strategy using a clinical feature-based screening questionnaire (SQ) (A-tool).

Methods: Finding axSpA (FaxSpA) was single-centre prospective study involving patients with chronic back pain (CBP). The A-tool, consisting of a three-question prescreen and eight-question SQ, was distributed to patients via the patient communication portal and university Facebook page. Patients with affirmative responses on all three prescreen questions, and three or more questions on SQ were eligible for study visit. Enrolled patients underwent history, physical examination, labs (CRP and HLA-B27) and imaging studies (X-ray and MRI of the pelvis). The clinician's judgement was considered the gold standard for diagnosing axSpA.

Results: Eighty-six of the 100 enrolled patients completed all the study procedures, and 29 (34%) were diagnosed with axSpA. Seven patients had AS, and 22 had non-radiographic axSpA. Sensitivity and specificity of the individual A-tool questions for diagnosing axSpA ranged from 0.03 to 0.86 and 0.14 to 0.96, respectively. Positive likelihood ratios (+LR) of the individual items in the A-tool ranged from 0.84 to 1.34. There was low to moderate agreement between the patient responses on the online A-tool and the corresponding physician-confirmed responses.

Conclusion: A tool-based strategy for self-referral of CBP patients is a simple, practical and feasible approach for early diagnosis of axSpA. We need a larger prospective study to validate our findings.