Background: The classic conception of pain etiology in rheumatologic disease is nociceptive pain - tissue injury and inflammation signaling through peripheral and central nerve fibers. But this can be mixed with other pain etiologies, including nociplastic, augmented pain experience due to central sensitization. The pain of fibromyalgia (FM) is nociplastic, occurs in 10-30% of rheumatologic disease patients, and its presence can influence disease severity assessment.
Objectives: 1) Ascertain the prevalence of FM and Widespread Pain (WP) in the CorEvitas psoriatic arthritis (PsA) registry as assessed by the Widespread Pain Index (WPI) and Symptom Severity Scale (SSS) questionnaires. 2) Characterize the demographic and clinical factors associated with FM and WP. 3) Ascertain the association of FM and WP on the Clinical Disease Activity in Psoriatic Arthritis (cDAPSA) score and other disease activity measures.
Methods: PsA registry patients completing the WPI/SSS questionnaires since May 2020, at their most recent visit recorded in the registry, were analyzed.
Results: The analysis included 1823 PsA patients; 11.1% fulfilled FM definition and 20.6% fulfilled WP definition. Several factors were associated with FM definition including female sex, depression/anxiety, impaired function, increased body mass index (BMI), and increased number of comorbidities. cDAPSA, patient pain and global, and tender joint count were twice as severe in patients with FM compared to those without.
Conclusion: Fibromyalgia prevalence is elevated in PsA and is associated with elevated disease measures, confounding reliable disease assessment for treat-to-target goals. Identification of fibromyalgia as an influential contextual factor in disease assessment is recommended.
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