C4A and major depressive disorder: Data are presented as median (interquartile range). ESSDAI - EULAR Sjögren ́s Syndrome Disease activity. ESSPRI - EULAR Sjögren ́s Syndrome Patient Reported Index. HADS - Hospital Anxiety and Depression Scale. ESR - erythrocyte sedimentation rate. CRP - C-reactive protein. RF - rheumatoid factor. C3 - complement component C3. C4 - complement component C4. IL-6 - interleukin-6.