Background/Purpose: To determine whether there is an excess prevalence of chronic widespread body pain  (CWP) in patients with Ankylosing spondylitis (AS).

Methods:   Patients were participants in the Scotland and Ireland Registry for Ankyolsing Spondylitis (SIRAS), an ongoing study of patients attending secondary care in Scotland who had received a clinical diagnosis of AS.  The study collected information on clinical features , including extra-spinal manifestations, BASDAI and BASFI from medical records, and patient-reported data by self-completion questionnaires (including fatigue measured by the Chalder Fatigue Scale (CFS)).  Information on CWP was collected by four-view body manikins and required to satisfy the definition used in the ACR 1990 criteria for FM (ACR-CWP) – i.e. chronic pain (>3 months) in 2 contralateral body quadrants, plus axial pain.  We believed the reporting of CWP among AS patients would be strongly influenced by spinal disease and, thus, would be difficult to interpret.  Therefore, we evaluated the total number of painful body regions reported (up to a maximum of 30) and used an alternative definition for CWP (aCWP) requiring chronic pain in 2 contralateral body quadrants, but excluding pain in the axial skeleton and/or the buttocks.  Population data on the prevalence of CWP (using the same definitions) was from the MUSICIAN study, a large two-centre UK population-based study of pain in adults.   Prevalence of aCWP was calculated in AS patients and reported as a standardised prevalence ratio (SPR).  Relationships with reporting aCWP in the AS population were evaluated by logistic regression and  expressed as odds ratios (OR) with 95% Confidence Intervals (95%CI).

Results: The analysis involved 547 AS patients in SIRAS (71% male; median age 52yrs) and a population sample of 14,680 persons from the MUSICIAN study.  The majority of the AS patients (89% of those tested) were HLA B27 positive, 81% had documented sacroiliitis, 34% had peripheral joint involvement and 29% had a history of uveitis.  24% had ever been prescribed anti-TNF drugs.  The prevalence of ACR-CWP among AS patients was 55.0% The number of non-spine body regions in which pain was reported was significantly higher in AS patients (median=5) than the general population (median=2) (Mann-Whitney p<0.001).  The prevalence of aCWP was 53.4% and the SPR in AS patients using this alternative definition was (284; 95%CI 260-307).  Prevalence of aCWP was higher among women than men (OR: 1.56; 95%CI: 1.07-2.27), and amongst those of lower education (school vs university education 1.89; 1.14-3.14); those unemployed due to ill-health (5.11; 2.57-10.17, vs those in paid employment); and those with a BASDAI or BASFI score ≥4 (3.94; 2.38-6.49, and 3.75; 2.24-6.25, respectively).  Similarly, high levels of fatigue (CFS >4) (2.86, 2.01-4.08) and past or current use of anti-TNF agents (1.63; 1.07-2.49) were also associated with aCWP.

Conclusion: The age and sex adjusted prevalence of CWP (using a modified definition more suited to AS patients) was almost three times higher in AS patients than in the general population, and was related to both individual and clinical factors. The identification of such symptoms in AS patients is challenging but important for management.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/do-patients-with-ankylosing-spondylitis-have-an-excess-prevalence-of-chronic-widespread-pain-results-from-the-scotland-and-ireland-registry-for-ankylosing-spondylitis-siras-and-the-musician-study/