Objective: To determine the frequency of neuropathic pain (NeP) and potentially related new factors including fibromyalgia, vitamin D and medication use in ankylosing spondylitis (AS) patients. Methods: In total, 102 patients with AS were prospectively enrolled in this study and evaluated for pain severity (visual analog scale, VAS), disease activity (the Bath Ankylosing Spondylitis Disease Activity Index, BASDAI), fibromyalgia and current medication use. The presence of NeP was also assessed using the painDETECT questionnaire. Blood samples were taken from all patients to analyze serum 25-hydroxyvitamin D and inflammatory marker levels. Results: NeP component 32 (21 [20.6%]; clearly NeP and 11 [10.8%]; mixed NeP) was present in patients with AS. Compared to those without NeP, they had significantly higher VAS and BASDAI scores (p=0.022 and 0.003, respectively). In addition, there was a highly significant difference of frequency of fibromyalgia between patients with and without NeP (50.0% vs. 5.7%, p＜0.001). Vitamin D status and medication use were comparable for patients with and without NeP. Logistic regression analysis revealed that only fibromyalgia was a significant predictor of NeP. Conclusion This study confirmed that about one-third of AS patients have the NeP component. In addition, NeP was found to be associated with the frequency of fibromyalgia. However, no relation was found between NeP and vitamin D status and medication use in AS.

Objective: To determine the frequency of neuropathic pain (NeP) and potentially related new factors including fibromyalgia, vitamin D and medication use in ankylosing spondylitis (AS) patients. Methods: In total, 102 patients with AS were prospectively enrolled in this study and evaluated for pain severity (visual analog scale, VAS), disease activity (the Bath Ankylosing Spondylitis Disease Activity Index, BASDAI), fibromyalgia and current medication use. The presence of NeP was also assessed using the painDETECT questionnaire. Blood samples were taken from all patients to analyze serum 25-hydroxyvitamin D and inflammatory marker levels. Results: NeP component 32 (21 [20.6%]; clearly NeP and 11 [10.8%]; mixed NeP) was present in patients with AS. Compared to those without NeP, they had significantly higher VAS and BASDAI scores (p=0.022 and 0.003, respectively). In addition, there was a highly significant difference of frequency of fibromyalgia between patients with and without NeP (50.0% vs. 5.7%, p＜0.001). Vitamin D status and medication use were comparable for patients with and without NeP. Logistic regression analysis revealed that only fibromyalgia was a significant predictor of NeP. Conclusion This study confirmed that about one-third of AS patients have the NeP component. In addition, NeP was found to be associated with the frequency of fibromyalgia. However, no relation was found between NeP and vitamin D status and medication use in AS.