The proposed referral parameters have proven useful when applied in primary care in identifying patients with AS/pre-radiographic axial SpA among young to middle-aged patients with chronic low back pain.

Both referral strategies demonstrated comparable performance in identification of patients with axial SpA. Strategy 1 might be preferred as an easy and reliable screening method for axial SpA at the primary care level.

Objective. To determine Th1 and Th2 cytokine production in patients with reactive arthritis (ReA) in relation to disease outcome and in comparison with rheumatoid arthritis (RA). Methods. Secretion of tumor necrosis factor (TNF), interferon-, interleukin-10 (IL-10), and IL-4 by peripheral blood mononuclear cells (PBMC) from 53 patients with early ReA (disease duration <8 weeks, 64% HLA-B27 positive) and 30 patients with early, untreated RA (disease duration <6 months) was determined by enzyme-linked immunosorbent assay (ELISA) after ex vivo stimulation. Intracellular cytokine staining with quantification of positive T cells by fluorescence-activated cell sorting (FACS) was performed in 12 ReA patients and 12 RA patients. In 27 ReA patients, cyto-kine secretion was measured again after 3 months. Patients were followed up for 1 year, and cytokine patterns were correlated with disease duration. Results. TNF secreted by whole PBMC and by T cells was significantly lower, by ELISA and by FACS, in ReA patients than in RA patients, while no significant differences were detected for the other cytokines. ReA patients with a disease duration of >6 months showed significantly lower TNF secretion than patients with a disease duration of <6 months (mean SD 385 207 pg/ml versus 684 277 pg/ml; P 0.003). Furthermore, low TNF secretion after 3 months also correlated significantly with a more chronic course of disease. HLA-B27 positive patients secreted less TNF than did those who were B27 negative (338 214 pg/ml versus 512 207 pg/ml; P 0.05), and patients with a more chronic course had a higher frequency of B27 positivity (47% versus 80%; P 0.01). Among the 27 HLA-B27 positive patients, TNF secretion in those with a disease duration of >6 months was lower than that in the 7 with a disease duration of <6 months (308 167 pg/ml versus 562 308 pg/ml; P 0.04). Conclusion. Low TNF secretion and HLA-B27 status correlate with longer disease duration in ReA patients, possibly with an additive effect. The diminished TNF production might reflect a state of relative immunodeficiency contributing to bacterial persistence in ReA.

Non-radiographic axial SpA represents an important differential diagnosis of back pain, especially in patients with recent symptom onset.

ObjectiveInflammatory back pain (IBP), the key symptom of axial spondyloarthritis (axSpA), including ankylosing spondylitis, has been proposed as a screening test for patients presenting with chronic back pain in primary care. The diagnostic accuracy of IBP in the rheumatology setting is unknown.MethodsSix rheumatology centres, representing secondary and tertiary rheumatology care, included routinely referred patients with consecutive chronic back pain with suspicion of axSpA. IBP (diagnostic test) was assessed in each centre by an independent (blinded) rheumatologist; a second (unblinded) rheumatologist made the diagnosis (axSpA or no-axSpA), which served as reference standard.ResultsOf 461 routinely referred patients, 403 received a final diagnosis. IBP was present in 67.3%, and 44.6% (180/403) were diagnosed as axSpA. The sensitivity of IBP according to various definitions (global judgement, Calin, Berlin, Assessment of SpondyloArthritis international Society criteria for IBP) was 74.4%–81.1 % and comparable to published figures, whereas the specificity was unexpectedly low (25.1%–43.9%). The resulting positive likelihood ratios (LR+) were 1.1–1.4 and without major differences between sets of IBP criteria. The presence of IBP according to various definitions increased the probability of axSpA by 2.5%–8.4% only (from 44.6% to 47.1%–53.0%).ConclusionsThe diagnostic utility of IBP in the rheumatology setting was smaller than expected. However, this was counterbalanced by a high prevalence of IBP among referred patients, demonstrating the effective usage of IBP in primary care as selection parameter for referral to rheumatology. Notably, this study illustrates potential shifts in specificity and LR+ of diagnostic tests if these tests are used to select patients for referral.