SSB and Down syndrome: *Mean ± standard deviation; **Median (interquartile range); *** Reference values in Appendix 1; ◊: At least once during follow-up; ANA: Antinuclear antibodies; Anti-SSA: Anti-Sjögren's syndrome-related antigen A; Anti-SSB: Anti–Sjögren's syndrome-related antigen B; ESR: Erythrocyte sedimentation rate; ESSDAI: EULAR Sjögren's syndrome disease activity index; NS: Non significant.