Identifying Axial Spondyloarthritis in Dutch Primary Care Patients, Ages 20–45 Years, With Chronic Low Back Pain

Abstract

Objective. To identify axial spondyloarthritis (SpA) in Dutch primary care patients with chronic low back pain (CLBP), and to design a simple referral model for general practitioners (GPs) that would identify patients at risk for axial SpA. Methods. Patients (ages 20 -45 years) with CLBP were identified from GP records. Assessments included inflammatory back pain questionnaires, medical interviews, physical examinations, HLA-B27, C-reactive protein level, conventional radiography, and magnetic resonance imaging. The outcome measure was axial SpA defined by the Assessment of SpondyloArthritis international Society (ASAS) criteria. Multivariable regression analysis with bootstrapping was used to develop the referral model. Results. A total of 364 patients (mean ؎ SD age 36.3 ؎ 6.8 years) was recruited with a median symptom duration of 9.0 years. Eighty-six patients (24%) fulfilled the ASAS criteria for axial SpA. Of all potential determinants, the ASAS inflammatory back pain questionnaire, good response to nonsteroidal antiinflammatory drugs, family history of SpA, and symptom duration were identified as most relevant for diagnosing axial SpA by multivariable regression analysis related to axial SpA. The shrunken regression coefficients were, respectively, 1.04, 0.83, 0.73, and 0.23. The combination of these 4 items proved a useful area under the receiver operating characteristic curve of 0.75 (SE 0.03). In a simplified score model, at the suggested cutoff value of 1.5, the sensitivity was 83% and specificity was 59%. Conclusion. This study shows that 1 of 4 primary care patients with CLBP was classified as having axial SpA. A preselection in primary care based on a combination of clinical items may be useful to facilitate the identification of patients at risk of axial SpA.

The ASAS Criteria for Axial Spondyloarthritis: Strengths, Weaknesses, and Proposals for a Way Forward

“…In line with our earlier findings among patients with Bspondylitis disease without radiographic sacroiliitis^ [12], there is a relative preponderance of women among patients with nr-axSpA as compared to those with AS [16,17]. The prevalence of HLA-B27 among axSpA patients in population-based studies varies widely depending on how such patients were ascertained [15][16][17].…”

“…This type of bias is unlikely in the Norwegian study as the 17 % prevalence of HLA-B27 in the group of patients with CBP with onset before age 45 is almost the same as in the general population (15.9 %) of that region [16]. In the Dutch study, on the other hand, the prevalence of HLA-B27 of only 5.5 % in the group of patients with CBP with onset before age 45 is even lower than in the general Dutch population (8.8 %) (Table 3) [17,18]. This finding is most likely due to misclassification bias where the ASAS criteria misclassified HLA-B27+ non-axSpA as axSpA, i.e., if the criteria lack discriminative power to differentiate between non-specific CBP and Btrue^axSpA.…”

“…The ASAS classification criteria have been applied in several studies and settings, and the reported prevalence of axSpA has been estimated to be at least two to three times that of classical AS (by modified New York criteria) [15][16][17]. In line with our earlier findings among patients with Bspondylitis disease without radiographic sacroiliitis^ [12], there is a relative preponderance of women among patients with nr-axSpA as compared to those with AS [16,17].…”

“…In a Dutch study, in the Rotterdam region, case records of 12,477 patients from general practitioners' registers were reviewed, and 1106 of them (8.9 %) were found to have ever been registered with non-specific low back pain and they were invited by letter [17]. Eligibility was further checked via an interview by telephone, and responders were eligible if they had current CBP for >12 weeks and had no contraindications for MRI, had no back injury, and were not pregnant.…”

The Early Diagnosis and Clinical Features of Axial Spondyloarthritis at the European Congress of Rheumatology 2015

“…Диагноз аксСпА устанавливался по критериям ASAS. Исследовались следующие стратегии: стратегия Brandt [4], MASTER [5], RADAR [6], двухступенчатая стра-тегия [7], CaFaSpA [8], новые рекомендации ASAS [9]. Наибольшую чувствительность и специфичность показали стратегии [4][5][6], включавшие МРТ КПС, HLA-B27 и вос-палительную боль в спине (ВБС).…”