Central Sensitization in Spondyloarthritis: Implications for Personalized Medicine

Background: Central sensitization (CS) has been held responsible for both persistent pain and high disease activity scores in Spondyloarthritis (SpA). The Central Sensitization Inventory (CSI) is a questionnaire used to determine CS frequency: a score of at least 40 is associated with a high likelihood of CS. Objectives: To investigate the prevalence of CS in our cohort and its association with clinical characteristics of patients and their quality of life. Methods: Adult patients with a diagnosis of Psoriatic Arthritis (PsA) or Axial Spondyloarthritis (AxSpA) who were also classifiable according to ClASsification criteria for Psoriatic Arthritis (CASPAR) and Assessment of SpondyloArthritis international Society (ASAS) criteria respectively, and regularly followed at the SpA outpatient clinic of our Unit were consecutively enrolled from April to November 2023. Their epidemiologic, clinical and clinimetric data were collected, as well as patient-reported outcome measures (PROMs) [CSI, Health Assessment Questionnaire (HAQ), FACIT-Fatigue (FACIT-F), SHORT-FORM 36 (SF-36), and Hospital Anxiety and Depression Scale (HADS)]. Considering the definition of "difficult-to-treat" rheumatoid arthritis, we defined as "multi-failure" those patients who were treated with more than two biologic disease-modifying anti-rheumatic drugs (bDMARDs) with different mechanisms of action. Intergroup comparisons were assessed by using Chi-square, t-test and ANOVA. p-values < 0.05 were considered significant. Results: A total of 100 patients were enrolled, 46 male (46.0%) and 54 female (54.0%), with a mean age of 59.4 ± 9.8 years and a mean disease duration of 14.8 ± 10.1 years; 79 patients (79%) had a diagnosis of PsA and 21 (21%) of AS. Forty-two patients (42.0%) had a CSI score ≥ 40. Significant correlations were found between a CSI score ≥ 40 and female sex (p = 0.004), the occurrence of enthesitis (p = 0.05), DAPSA-CRP (p = 0.02) and ASDAS scores (p = 0.03), a multi-failure condition (p = 0.01), fibromyalgia (FM) (p = 0.004), thyroid disease (p = 0.016) and obesity (p = 0.047). Regarding PROMs, significant correlations were found between CSI and values of HADS (both anxiety and depression), FACIT-F, HAQ and all the domains of SF-36 (p-value < 0.0001). Conclusions: Our data confirmed that more than 40% of SpA patients had CSI values ≥ 40 and underlined how CS could widely impair their disease burden. A routinary evaluation of CS and a multifactorial biopsychosocial perspective in the diagnosis and management of chronic pain in patients with SpA could help rheumatologists in improving their quality of care.