C3 and lymphopenia: Thirty‐five percent of pSS patients received hydroxychloroquine (HQ) treatment, and this group was significantly enriched in severe individuals (35 vs. 16%; P = 0.002), the presence of extra‐glandular manifestations (76 vs. 32%; P < 0.0001), and a trend to more marked alterations in levels of parameters associated with pathology such as lymphopenia, higher levels of IgG, and significantly lower levels of complement C3 (Appendix Table S1).