Some Early Spondyloarthritis Features More Definitive than Others

Patients with early axial spondyloarthritis exhibit different symptoms from patients with long-standing axial disease. Sacroiliitis on MRI and peripheral arthritis appear to be the best indicators of disease in this group, researchers report.

In the study, published online May 9 in Arthritis Care & Research, researchers evaluated the validity of various spondyloarthritis (SpA) features in a cohort of patients from Spain. 

Spondyloarthritis is a group of inflammatory diseases with an estimated global prevalence of ranging from 0.18 to 1.9 percent. Among patients with ankylosing spondylitis, many years can pass before symptoms, such as back pain, appear. This long-time horizon makes the early diagnosis of spondyloarthritis a major challenge for physicians.

Led by Beatriz Joven, M.D, of the University Hospital La Paz in Spain, this longitudinal study was conducted with patients the ESPeranza program cohort of patients who were suspected to have early spondyloarthritis. The goal of the study was to better understand the diagnostic value and validity of key spondyloarthritis factors as a means to improve early diagnosis. In particular, sensitivity, specificity, predictive value and the likelihood ratio of each feature were calculated.

“The diagnostic value of SpA features in the cohort of patients with early axial SpA seems to be different than in patients with longstanding axial disease, and this difference has clinical relevance,” wrote Dr. Joven and colleagues. 

The study

This was a longitudinal, multi-center study conducted with 775 patients suspected to have spondyloarthritis of which 665 had predominantly axial symptoms and 516 of these patients were diagnosed with axial SpA. Patients (mean age 33 years) were exhibiting axial and peripheral symptoms lasting three to 24 months.

Associated conditions

Sacroiliitis on radiography at the baseline was discovered in 110 patients (21%, 3.1 likelihood ratio), indicating a definitive diagnosis. An MRI showed that 48% of 257 patients with SpA were positive according to the Outcome Measure in Rheumatology (OMERACT) criteria (6.6 positive likelihood ratio). Arthritis had a likelihood ratio of 8.9.

Alternative buttock pain affected 34% of patients (2.9 likelihood ratio) and inflammatory back pain - which also presents as mechanical back pain - affected 27% of patients (2.3 likelihood ratio). Inflammatory back pain should not be considered a key symptom in the early SpA population. As observed in other cohorts of patients suspected of having axial SpA, if only inflammatory back pain were considered, we would miss many patients with SpA,” researchers wrote.

Enthesitis, arthritis and dactylitis were less frequently reported, and sensitivity was low (17%, 18%, and 5%, respectively). Inflammatory bowel disease (IBD) was diagnosed in 24 patients (5%) and had a positive likelihood ratio of 3.6. Fourteen patients (3%) described previous diarrhea, cervicitis or urethritis and were diagnosed with SpA, while no one in the non-SpA group reported these symptoms.

CRP and ESR levels were elevated in 63 SpA patients (12%, 2.6 likelihood ratio). HLA–B27 positivity was seen in 245 patients (48%, 2.8 likelihood ratio). “In some geographic areas, HLA–B27 status determination as a key criterion is questionable because it underestimates SpA diagnosis in HLA–B27–negative patients,” researchers wrote.

The spondyloarthritis features that had the lowest diagnostic utility included family history of spondyloarthritis (positive LR 1.5) and a good response to NSAIDS (positive LR 1.6).

The spondyloarthritis features explored in the study were obtained from the Berlin diagnostic algorithm and Assessment of SpondyloArthritis international Society classification criteria. The Berlin criteria is a diagnostic algorithm based on the calculation of the likelihood ratio product of currently available diagnostic features for axial spondyloarthritis.

Patients with early spondyloarthritis have similar disease characteristics and worse function than patients with long-standing disease, which creates a socioeconomic burden on both the patient and society. Thus, early and better diagnostic criteria for spondyloarthritis are important for treating this disease.

Disclosures:

This research was funded by the Instituto de Salud Carlos III and FONDOS FEDER.

References:

Joven, B. E., Navarro-Compán, V., Rosas, J., et al. “Diagnostic Value and Validity of Early Spondyloarthritis Features: Results From a National Spanish Cohort,” Arthritis Care & Research. Published online May 9, 2017. doi:10.1002/acr.23017.

Joven, B. E., Navarro-Compán, V., Rosas, J., et al. “Diagnostic Value and Validity of Early Spondyloarthritis Features: Results From a National Spanish Cohort,” Arthritis Care & Research. Published online May 9, 2017. doi:10.1002/acr.23017.