Fatigue in primary and associated Sjögren's disease: similar burden, distinct determinants.

OBJECTIVES

Fatigue is a disabling symptom in Sjögren's disease (SjD); however, its severity and related factors in associated SjD remain unclear. We compared fatigue severity among patients with primary Sjögren's disease (pSjD), associated SjD, and systemic autoimmune rheumatic diseases (SARDs) without SjD and identified fatigue-associated clinical and patient-reported factors in patients with pSjD and associated SjD.

METHODS

This cross-sectional study included 115 patients with pSjD, 125 with associated SjD, and 52 with SARDs without SjD. Fatigue was assessed using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) and EULAR Sjögren's Syndrome Patient Reported Index (ESSPRI). Clinical and laboratory parameters were analysed.

RESULTS

Fatigue was significantly more severe in pSjD and associated SjD than in SARDs without SjD (FACIT-F total: 30 vs. 36 vs. 42, p < 0.001), with no significant difference between pSjD and associated SjD. Patients with pSjD reported greater subjective symptom burden, including higher ESSPRI fatigue (7.0 vs. 5.0, p = 0.011) and dryness (7.0 vs. 5.0, p = 0.012) scores. In multivariate analysis, pain (pSjD: β -2.12, p < 0.001; associated SjD: β -0.79, p = 0.019) and dryness (pSjD: β -1.26, p = 0.002; associated SjD: β -2.07, p < 0.001) were independently related with fatigue in both groups. Fibromyalgia (β -15.4, p < 0.001) and arthritis (β -7.7, p = 0.006) were related only in pSjD, and C-reactive protein (β -1.53, p = 0.029) only in associated SjD. Fatigue was not linked with systemic disease activity (ESSDAI) in pSjD.

CONCLUSIONS

Fatigue is a major burden across the SjD spectrum, with similar severity in pSjD and associated SjD but distinct contributing mechanisms. Key Points • Fatigue severity was comparable between pSjD and associated SjD; however, distinct factors were associated with fatigue. • Fibromyalgia and arthritis were independently associated with fatigue in pSjD, whereas systemic inflammation contributed to associated SjD.