Overlapping Sjogren's syndrome (SS) is not uncommon in rheumatoid arthritis (RA) and considered as a probable detrimental factor of RA. But data on the impact of overlapping SS on RA therapeutic response is limited. Our current study aimed to identify the effect in a real-world cohort from 2009 to 2019.
The medical records of RA patients who visited the rheumatology clinic of our medical center from 2009 to 2019 were reviewed. Their composite disease activity scores at each follow-up point were collected. The therapeutic response between RA patients with SS (RA-SS) and without (RA-noSS) was compared. To correct confounders which may affect the therapeutic response, both propensity score matched and unmatched cohorts were analyzed by using the Cox proportional hazards model.
Among the 1099 RA patients, 129 (11.7%) overlapped with SS were validated by positive anti-SSA or a minor salivary gland biopsy with histological changes suggestive of SS. After propensity score matching based on their baseline characteristics, 126 of 129 RA-SS and 126 of 970 RA-noSS patients were statistically extracted. Overlapping SS was associated with a 29%, 26%, 18%, and 22% lower probability of reaching remission defined by DAS28-ESR, DAS28-CRP, SDAI, and CDAI in RA patients, respectively. Similar decreased probability of reaching low disease activity was also observed. Although ESR was most significantly affected (HR 0.69, 95% CI 0.61-0.79), other component of composite RA disease activity score was also affected by overlapping SS. Stratification by age, RF/ACPA status, or baseline DAS28-CRP was not associated with change of results.
Overlapping SS is associated with lower probability of reaching remission or low disease activity in RA patients and should be regarded as one of the poor prognostic factors.