Objective: To study differences in pain reports between patients with ankylosing spondylitis (AS) and nonradiographic axial spondyloarthritis (nr-axSpA), and to assess how pain sensitivity measures associate with disease and health outcomes.Methods: Consecutive patients with axial SpA (axSpA) were enrolled in the population-based SPARTAKUS cohort (2015–2017) and classified as AS (n = 120) or nr-axSpA (n = 55). Pain was assessed with questionnaires (intensity/duration/distribution) and computerized cuff pressure algometry to measure pain sensitivity (pain threshold/pain tolerance/temporal summation of pain). Linear regression models were used to compare pain measures between patients with AS and nr-axSpA, and to assess associations between pain sensitivity measures and disease and health outcomes.Results: Of 175 patients with axSpA, 43% reported chronic widespread pain, with no significant differences in any questionnaire-derived or algometry-assessed pain measures between patients with AS and nr-axSpA. Lower pain tolerance was associated with longer symptom duration, worse Ankylosing Spondylitis Disease Activity Score using C-reactive protein (ASDAS-CRP), Bath Ankylosing Spondylitis Functional Index, and Bath Ankylosing Spondylitis Metrology Index (BASMI), more pain regions, unacceptable pain, worse Maastricht AS Enthesitis Score (MASES), fatigue, anxiety, and health-related quality of life. Further, lower pain threshold was associated with worse ASDAS-CRP and MASES, whereas higher temporal summation was associated with longer symptom duration, unacceptable pain, and worse BASMI.Conclusion: Chronic pain is common in axSpA, with no observed differences in any pain measures between patients with AS and nr-axSpA. Further, higher pain sensitivity is associated with having worse disease and health outcomes. The results indicate that patients with AS and nr-axSpA, in line with most clinical characteristics, have a similar pain burden, and they highlight large unmet needs regarding individualized pain management, regardless of axSpA subgroup.

To examine faecal calprotectin (F-calprotectin) levels and presence of anti-Saccharomyces cerevisiae antibodies (ASCA) and their associations with disease subtype and current status in axial SpA (axSpA). F-calprotectin and ASCA in serum were compared between consecutive patients with a clinical axSpA diagnosis, classified as non-radiographic axSpA (nr-axSpA; n = 40) or AS (n = 90), and with healthy controls (n = 35). Furthermore, standard axSpA outcome measures were compared between axSpA patients (nr-axSpA and AS combined) with elevated vs normal F-calprotectin, ASCA IgA and IgG, respectively. Elevated F-calprotectin (⩾50 mg/kg) was observed in 27% of nr-axSpA patients, 38% of AS patients and 6% of controls. F-calprotectin was significantly higher in AS vs nr-axSpA [AS: geometric mean 41 (95% CI 32, 54) mg/kg; nr-axSpA: 24 (95% CI 16, 38) mg/kg; P = 0.037], and in each axSpA subtype vs controls. Overall, worse disease activity and physical function scores were observed among axSpA patients with elevated vs normal F-calprotectin levels, with significant differences regarding patient's visual analogue scale for global health, ASDAS using CRP, and BASFI (adjusted for age, sex, NSAID use, anti-rheumatic treatments, and CRP). ASCA titres and seropositivity (⩾10 U/ml) were similar in nr-axSpA (IgA/IgG-seropositivity: 8%/26%) and AS (7%/28%), and clinical outcome measures did not differ between patients with elevated vs normal ASCA IgA or IgG, respectively. Compared with controls (IgA/IgG-seropositivity: 0%/17%), ASCA IgA was significantly higher in both axSpA subtypes, and IgG was significantly higher in the AS group. In patients with axSpA, gut inflammation measured by elevated F-calprotectin is associated with worse disease activity and physical function, and may be a marker of more severe disease.

Objective: To study chronic widespread pain (CWP) over time in patients with spondyloarthritis (SpA), and to identify risk factors for development and persistence of CWP. Methods: In this cohort study with baseline and 2.5 year follow-up postal surveys, patients with ankylosing spondylitis (AS) and undifferentiated spondyloarthritis (USpA) (47% women) answered questions regarding pain, and were categorized as no chronic pain (NCP), chronic regional pain (CRP), or CWP. For each risk factor candidate (disease duration, body mass index, smoking, and patient-reported outcome measures), logistic regression analyses with CWP as the main outcome were performed separately, together with a basic model including age, gender, and SpA subgroup. Results: Altogether, 644 patients could be categorized at both time-points, yielding similar prevalence estimates at baseline and follow-up, although 38% transitioned between pain groups. Risk factors (odds ratio; 95% confidence interval) for development of CWP included more pain regions (1.36; 1.20‒1.53), higher pain intensity (1.35; 1.20‒1.52), worse fatigue (1.25; 1.13‒1.38), and worse global health (1.35; 1.19‒1.54). Persistent CWP was reported by 72%. In addition to factors predicting development of CWP, higher age (1.02; 1.00‒1.04), female gender (1.82; 1.06‒3.10), and anxiety (1.07; 1.00–1.14) also predicted persistence. Conclusion: The prevalence of CWP remained high over time, but with individual transitions between the pain groups. The development and persistence of CWP were predicted by more pain and worse health, with the addition of female gender and higher age for persistent CWP. Special attention and treatment alternatives for patients with SpA and concomitant CWP are essential in the clinic.

Chronic pain, regional or widespread, is a frequent and multidimensional symptom in arthritis. There is still limited information on chronic pain in spondyloarthritis, which is important to recognize for adequate diagnosis and treatment. Our objective was to study differences in prevalence of chronic widespread pain in two spondyloarthritis subgroups: ankylosing spondylitis (AS) and undifferentiated spondyloarthritis (USpA). A population-based postal survey involving questions on the duration, distribution, and intensity of pain was answered by 940 patients with AS (ICD-10 M45.9) or USpA (ICD-10 M46.1-0, M46.8-9). The patients were categorized as having chronic widespread pain, chronic regional pain, or no chronic pain, and prevalence estimates for the pain groups were calculated, including age- and sex-adjusted prevalence. The prevalence of chronic widespread pain was 45.3% in AS vs. 49.3% in USpA, and that of chronic regional pain was 17.7% vs. 21.9% (p = 0.033). More women than men reported having chronic widespread pain (54.1% vs. 41.2%, p ≤ 0.001), while the sex distribution for chronic regional pain was equal. Reports of pain intensity were equal in AS and USpA, with no significant difference in pain intensity between women and men who had chronic regional pain or chronic widespread pain. In the multiple logistic regression analysis, chronic widespread pain was associated to female sex, being an ever-smoker, and having a higher body mass index, controlled for SpA subgroup and disease duration. The prevalence of chronic widespread pain in patients with AS and USpA is high, and with a female predominance, but with no difference in pain intensity between women and men. Chronic pain can complicate the clinical evaluation in patients with SpA, and highlights the need for a thorough clinical examination, including evaluation of inflammation and an accurate pain analysis, to individualize non-pharmacological and pharmacological treatment decisions.