Systemic auto-inflammatory manifestations in patients with spondyloarthritis.

Objectives: (1) characterizing a group of spondyloarthritis (SpA) patients with systemic auto-inflammatory symptoms (S-SpA); (2) comparing SpA features with and without auto-inflammatory symptoms; (3) comparing the auto-inflammatory features of S-SpA and Still's disease (SD).

Methods: Retrospective observational study. Clinical data of adult and pediatric patients with S-SpA, SD or SpA were collected retrospectively and analyzed.

Results: Forty-one subjects with S-SpA, 39 with SD and 42 with SpA were enrolled. The median latency between systemic and articular manifestations in S-SpA was 4.4 (IQR: 7.2) years. S-SpA and SpA had similar frequency of peripheral arthritis and enthesitis (N.S.), while tenosynovitis was more frequent (P=0.01) and uveitis less frequent (P<0.01) in S-SpA. MRI showed signs of sacroiliac inflammation and damage in both S-SpA and SpA equally (N.S.). S-SpA patients had less corner inflammatory lesions (P<0.05) and inflammation at the facet joints (P<0.01), more interspinous enthesitis (P=0.01) and inter-apophyseal capsulitis (P<0.01). Compared to SD, S-SpA patients had lower-grade fever (P<0.01), less rash (P<0.01) and weight loss (P<0.05), but more pharyngitis (P<0.01), gastrointestinal symptoms (P<0.01) and chest pain (P<0.05). ESR, CRP, WBC, ANC, LDH tested higher in SD (P<0.01). Resolution of systemic symptoms was less frequent in S-SpA than SD on corticosteroid (P<0.01) and methotrexate (P<0.05) treatment. When considering all SD patients, a complete response to corticosteroids in the systemic phase significantly reduced the likelihood of developing SpA (OR=0.06, coefficient -2.87 [CI: -5.0 to -0.8]).

Conclusions: SpA should be actively investigated in patients with auto-inflammatory manifestations, including undifferentiated auto-inflammatory disease and SD.