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The median central sensitization, frequency of neuropathic pain, and frequency of fibromyalgia diagnosis were higher in patients with axSpA when compared with controls.
Central sensitization (CS), a common symptom among patients with axial spondyloarthritis (axSpA), was associated with worse functional status and quality of life, as well as higher disease activity, when compared with patients without CS, according to a study published in Journal of Rheumatic Diseases.1
CS is defined as a type of nociplastic pain, with increased nociceptive sensitivity with either normal or sub-threshold afferent input from neurons in the central nervous system. It occurs due to neuroinflammation in the peripheral and central nervous systems.2
“Recently, it has been reported that 15% to 40% of inflammatory rheumatic diseases are accompanied by CS,” wrote Senem Şaş, MD, Division of Rheumatology, Department of Physical Medicine and Rehabilitation, Erciyes University School of Medicine, Kayseri, Turkey, and colleagues. “Although CS is considered common in FM patients, there are few reports state that CS negatively affects disease activity and quality of life in axSpA patients. In addition, pain, older age, worse health status, and female sex have been found to contribute to persistent widespread pain in spondyloarthritis (SpA).”
In the cross-sectional study, patients with axSpA who were followed up at a rheumatology outpatient clinic in Turkey, along with age- and sex-matched controls, were recruited between July 2021 and November 2021. Information including age, sex, medications, morning stiffness, duration of first symptoms, and duration of illness was collected.
To determine the effect of CS on quality of life, clinical parameters, and disease activity, investigators used the douleur neuropathique 4 (DN4) questions, the central sensitization inventory (CSI), 18-item Ankylosing spondylitis quality of life (ASQoL) questionnaire, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score with C-reactive protein (ASDAS-CRP), and the 2010 American College of Rheumatology (ACR) fibromyalgia criteria, among others. The CSI consists of 25 questions designed to evaluate emotional and somatic disorders. After obtaining all relevant information, the patient and control groups were then compared.
In total, 116 patients with axSpA and 95 controls participated in the study, with a mean age of 42 years. Most (81%) reported morning stiffness and 35.3% of patients were currently treated with biological drugs.
CS was identified in approximately half (46.6%, n = 54) of patients in the axSpA cohort, compared with only 13.7% of controls (P <.001). Patients diagnosed with CS had poor quality of life, high disease activity, and worse functionality when compared with those without CS (P <.001).
Additionally, the median CS, frequency of neuropathic pain (NP), and frequency of fibromyalgia diagnosis were higher in patients when compared with controls (P <.001). Conditions related to CS, such as anxiety and depression, were higher in the axSpA group than in the control group (P <.05). In the multivariate model, ASQoL scores and biologic drugs were independent risk factors for developing CS.
Investigators noted the study as the first to assess the coexistence of CS, NP, and FM in patients with axSpA as well as controls. The inclusion of a healthy control group, along with the evaluation of the domains of disease-related outcome measures in the axSpA cohort, also strengthened the study. However, the relatively small sample size, due to the COVID-19 pandemic, and the cross-sectional design limited the study as changes in CS could not be evaluated long-term.
“Overall, CS, FM, and NP need to be considered in the treatment plans of axSpA patients,” investigators concluded.