Clinical characteristics and risk factors for overlapping rheumatoid arthritis and Sjögren's syndrome

This study investigated the clinical characteristics and risk factors for overlapping rheumatoid arthritis and Sjögren's syndrome (RA/SS). Patients with RA/SS in Peking Union Medical College Hospital from January 2012 to January 2017 were retrospectively analysed and compared to those of sex- and age-matched RA or SS controls. Logistic regression analysis was used to identify risk factors. Altogether, 105 consecutive patients with RA/SS were enrolled. Ninety-seven (92.4%) of them were female, with a mean age of 51.5 ± 13.3 years or 45.2 ± 14.7years at the diagnosis of SS or RA, respectively. In addition to arthritis and Sicca symptom, patients with RA/SS had more visceral involvements including interstitial lung disease (ILD), and haematologic involvement, and received more glucocorticoid treatments than controls (p < 0.05). RA-onset, simultaneous-onset and SS-onset patients had significant differences in age at RA diagnosis, fever and thrombocytopenia (p < 0.05). Multivariate logistic analysis indicated that arthritis (OR = 44.804), rheumatoid factor (RF) (OR = 5.973), and anti-CCP (OR = 2.545) were independent risk factors for SS overlapping with RA. Xerostomia (OR = 3.960), ILD (OR = 6.210), and anti-SSA (OR = 24.640) were independent predictors of RA overlapping with SS. RA/SS patients have more visceral involvements. Our findings highlight the roles of arthritis/RF/anti-CCP and xerostomia/ILD/anti-SSA in the development of this overlapping disease.