A systematic review of primary Sjögren's syndrome in male and paediatric populations.

Primary Sjögren's syndrome (pSS) is a chronic multisystem autoimmune rheumatic disease characterised by female predominance. Although the disease is rare in the male and paediatric populations, it has been suggested that it may have a different disease phenotype, which has not been investigated before using a systematic approach. A systematic literature search of PubMed databases (updated to December 2016) was performed to identify all published data on the epidemiological, clinical and laboratory manifestations of pSS in the male and paediatric populations. The literature search of the male and paediatric pSS studies identified 2025 and 186 citations, respectively, out of which 7 and 5 fulfilled our inclusion criteria and were analysed further. The range of age at disease onset was 9.4-10.7 years for children and 39.4-56.9 years at diagnosis for male patients. We identified a prevalence of extra-glandular manifestations between 52.6-92.3% in the male population and 50.0-84.6% in children, while abnormal sialometry was only reported in the paediatric population, with a prevalence between 71.4 and 81.8%. There was a significant variation of positive serological markers, with anti-Ro antibodies reported between 15.7-75.0% and 36.4-84.6%, and anti-La antibodies between 5.6-51.7% and 27.3-65.4%, in the male and paediatric populations, respectively. The characteristics of pSS in the male and paediatric populations varied according to different studies. When compared to data available from pSS adult populations, children diagnosed with pSS reported less dryness and had a higher prevalence of parotitis, lymphadenopathy and systemic symptoms and male patients were younger at the time of diagnosis. This systematic review contributes to a better understanding of the epidemiology of pSS in rare populations. Large longitudinal cohort studies comparing male with female patients and adult with paediatric patients are needed.