Neuropathic Pain Component in Axial Spondyloarthritis and the Influence on Disease Burden

Objectives: Patients with nonradiographic axial spondyloarthritis (nr-axSpA) and radiographic axSpA/ankylosing spondylitis (AS) have similar burden of disease; however, the potential influence of pain characteristics including the neuropathic pain (NeP) component has not been assessed yet. The aim of this study was first to assess frequency of NeP component in patients with axSpA and second to assess the potential influence of NeP on burden of disease. Methods: Adult patients who met the Assessment of SpondyloArthritis International Society classification criteria for axSpA were consecutively recruited. Patients were evaluated using the Douleur Neuropathique en 4 Questions interview and painDETECT questionnaire and subgrouped as patients with and without NeP. Results: Neuropathic pain component was present in 31.4% of patients with axSpA categorized according to Douleur Neuropathique en 4 Questions (31.6% in nr-axSpA vs 31.3% in AS, P = 0.964) and in 33.5% of patients categorized according to painDETECT (35.1% in nr-axSpA vs 32.8% in AS, P = 0.762). Pain characteristics were quite similar between patients with nr-axSpA and AS. Women tented to have more frequent NeP. Patients with NeP component had significantly higher scores in visual analog scale of pain, patient and physician global, fatigue, Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity Score using C-reactive protein, depression, anxiety scores, and physical functions; poorer quality of life (QoL); and similar frequency of fibromyalgia compared with patients without NeP component. In multivariable analysis, having NeP was associated with QoL measures (Ankylosing Spondylitis Quality of Life and Short-Form 36 physical component score) and visual analog scale of fatigue. Conclusions: Nearly one third of patients with axSpA may have NeP component regardless of having nr-axSpA or AS. Neuropathic pain component may contribute worsened QoL and poorer patient-reported outcome data and should be kept in mind during patient evaluation.