Background Several referral strategies for axial spondyloarthritis (axSpA) have been proposed. The goal of these strategies is to overcome the delay between the first symptoms and the final diagnosis of axSpA by supporting primary care physicians in recognizing potential axSpA patients. All referral strategies are tested in their original study population, however no direct comparison of the performance of different strategies in one study population is performed.
Objectives To evaluated six different referral strategies for axSpA in unselected young primary care patients with chronic low back pain (CLBP) and secondly to find the optimal referral strategy for daily practice.
Methods The referral strategies were evaluated in a large Dutch primary care population of unselected CLBP patients (18-45 years, CLBP ≥3 months, back pain onset <45 years). Patients already diagnosed with ankylosing spondylitis were not invited. Patients underwent a diagnostic work-up including, a standardized history, physical examination, HLA-B27 and CRP testing. A conventional radiograph and MRI of the sacroiliac joints were obtained. Definite axSpA was defined by the ASAS criteria. The following referral strategies were tested, listed by year of publication; the Brandt strategy1, MASTER2, RADAR3, the 2-step strategy4, the CaFaSpA strategy5, and the new ASAS recommendations6. For a description of the different strategies see Figure 1. The performance of the different referral models was assessed by sensitivity, specificity, area under the curve (AUC) and positive predictive value (PPV).
Results In total 941 primary care CLBP patients participated (58% female, mean age 36.0 years), of those were 181 (19%) identified as axSpA, 54 of the 181 (30%) were newly diagnosed with ankylosing spondylitis. Almost all referral strategies had a good discriminative performance (AUC >0.7). (Table 1) The MASTER referral strategy had the most balanced sensitivity and specificity. The new ASAS proposal has the lowest AUC, lowest specificity and the lowest PPV.
Conclusions Almost all referral strategies had a good performance in this primary care cohort of CLBP patients. Strategies including imaging, HLA-B27 and inflammatory back pain (IBP) had the highest AUC and PPV. However imaging and blood tests are not always accessible in primary care, mainly due to high costs. The optimal strategy for primary care should include non-invasive referral parameters without additional costs such as IBP, good response to NSAIDs and family history.
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van Hoeven et al, 2014.
Poddubnyy et al, 2014
Acknowledgements An unrestricted research grant was provided by AbbVie.
Disclosure of Interest None declared