Sjögren's disease and concomitant fibromyalgia: clinical profile and implications for disease activity assessment

Fibromyalgia (FM) is more prevalent in patients with Sjögren's disease (SjD) than in the general population and a bidirectional association between the two conditions has been proposed. However, the clinical profile of patients with concomitant FM and SjD remains poorly characterized. This study aimed to assess the prevalence and clinical correlates of FM in a multicenter Italian cohort of patients with SjD. Patients fulfilling the 2016 ACR-EULAR classification criteria for SjD were retrospectively evaluated. FM was defined according to the 2016 diagnostic criteria. Clinical, serological, and therapeutic data were compared between patients with and without FM. Logistic regression models identified factors associated with FM. Among 267 patients with SjD (95% female, median age 60), FM was diagnosed in 30%. Patients with FM reported significantly higher symptom burden, as measured by the EULAR Sjögren's Syndrome Patient-Reported Index (median 7.7 vs. 6.0; p < 0.001), with all individual domains, namely pain, fatigue, and dryness, being significantly increased (p < 0.01, for all). In contrast, EULAR Sjögren's Syndrome Disease Activity Index scores were comparable between groups (p = 0.808). In the logistic regression model, three variables were independently associated with FM: higher symptom burden (adjusted odds ratio (aOR 1.36, 95% CI 1.13-1.62; p = 0.001), mixed anxiety-depressive disorder (aOR 3.24, 95% CI 1.13-9.30; p = 0.029), and corticosteroid use (aOR 2.76, 95% CI 1.02-7.48; p = 0.046). In patients with SjD, FM is associated with a higher symptom burden despite similar disease activity level. These findings highlight the need to distinguish symptom amplification from true inflammatory activity, limiting unnecessary corticosteroid use.