Development of new extra-glandular manifestations or associated auto-immune diseases after establishing the diagnosis of primary Sjögren's syndrome : A long-term study of the Antonius Nieuwegein Sjögren (ANS) cohort

Abstract

To investigate in a long-term study, the development of new extra-glandular manifestations (EGM) or associated auto-immune diseases (AID) from 1 year after establishing the diagnosis of primary Sjögren's syndrome (pSS). The primary goal was to examine the frequency and type of these manifestations and to find out which demographic, clinical and serological profile was most at risk. All outpatients diagnosed with primary Sjögren's syndrome were included in a retrospective study, with at least one check-up per year, from June 1991 until August 2015. Patients also fulfilling the criteria for concomitant connective tissue disorders were excluded. Data were collected with respect to the cumulative prevalence of a new EGM or associated AID. 140 patients were included in the final analysis. After 10 years of follow-up, the cumulative incidence of a new EGM or associated AID was 30.7%. The most frequent events were polyneuropathy, interstitial lung disease, (poly)arthritis, discoid lupus erythematosus (LE)/subacute cutaneous LE and Hashimoto's disease. Non-Hodgkin lymphoma was not diagnosed during the follow-up. Patients without chronic benign pain syndrome (CBP) (HR 2.13; 95% CI [0.94-4.76]; p = 0.061), but in particular those with cryoglobulins (HR 2.87; 95% CI [1.20-6.86]; p = 0.013), developed more events. Age at diagnosis, gender, the presence of ANA, anti-Ro/SSA, anti-La/SSB, IgM-RF, decreased levels of C3 or C4, or hypergammaglobulinaemia did not show any statistically significant differences. The burden of disease in pSS is higher than expected due to the development of EGM or associated AID. Therefore, we recommend long-term follow-up of all pSS patients, particularly those with cryoglobulinaemia.

Keywords: Associated auto-immune diseases; Cryoglobulinaemia; Extra-glandular manifestations; Long-term follow-up; Primary Sjögren’s syndrome.