BackgroundThe value of clinical items defining inflammatory back pain to identify patients with axial spondyloarthritis (SpA) in primary care is unclear.ObjectiveTo identify predictive clinical parameters for a diagnosis of axial SpA in patients with chronic back pain presenting in primary care.MethodsConsecutive patients aged <45 years (n=950) with back pain for >2 months who presented to orthopaedic surgeons (n=143) were randomised based on four key questions for referral to rheumatologists (n=36) for diagnosis.ResultsThe rheumatologists saw 322 representative patients (mean age 36 years, 50% female, median duration of back pain 30 months). 113 patients (35%) were diagnosed as axial SpA (62% HLA B27+), 47 (15%) as ankylosing spondylitis (AS) and 66 (21%) as axial non-radiographic SpA (nrSpA). Age at onset ≤35 years, improvement by exercise, improvement with non-steroidal anti-inflammatory drugs, waking up in the second half of the night and alternating buttock pain were identified as most relevant for diagnosing axial SpA by multiple regression analysis. Differences between AS and nrSpA were detected. No single item was predictive, but ≥3 items proved useful for good sensitivity and specificity by receiver operating characteristic modelling.ConclusionThis study shows that a preselection in primary care of patients with back pain based on a combination of clinical items is useful to facilitate the diagnosis of axial SpA.

This is the first study to show that patients with axSpA are more reliably identified in primary care by a strategy that includes HLA B27. Because of the two-step approach, the test needs to be performed in only about half of patients with chronic BP.

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Background The value of a combination of items defining inflammatory back pain (IBP) to screen for axial spondyloarthritis (SpA) in primary care has recently been studied. However, whether and how measurement of the HLA B27 status contributes to that is not clear. Objectives To study the additional value of HLA B27 determination as screening parameters for axial SpA in a cohort of patients with chronic back pain. Methods Consecutive patients <45 years (n=950) with back pain >2 months who presented to orthopedic surgeons (n=143) were randomized based on 4 primary key questions related to inflammatory back pain (IBP) for referral to rheumatologists (n=36) who made the diagnosis. HLA B27 was either assessed in primary or in secondary care. The primary outcome was the predictive value of a combination of items for a diagnosis of axial SpA. Logistic regression analyses and modeling techniques were used for the statistical analyses. Results Rheumatologists saw 322 randomly selected representative patients, mean age 36 years (y), 50% female, median duration of back pain 30 months: 113 patients were diagnosed as axial SpA (35%), 62% B27+, 47 as ankylosing spondylitis (AS, 15%), 66 as non-radiographic axial SpA (nr-axSpA, 21%). Major differences between AS and nr-axSpA have been described. Excluding HLA B27 from the analysis led to a list of criteria ≥4 of which had a sensitivity and specificity of 58.4 and 70.8%, respectively (area under ROC 69%). Adding HLA B27 to the analyses induced changes in the list of relevant items: past/present enthesitis came in, and the sensitivity (68.1%) but not the specificity (68.4%) of the criteria list improved (area under ROC 73.8%). Conclusions This study shows that patients with axial SpA can be identified by different methods in primary care. Combining HLA B27 and clinical items indicative of IBP increased the likelihood of having axial SpA in primary care. References Braun A, Saracbasi E, Grifka J, Schnitker J, Braun J. Identifying patients with axial spondyloarthritis in primary care: how useful are items indicative of inflammatory back pain? Ann Rheum Dis 2011;70:1782-7. Disclosure of Interest None Declared