C4A and arthritic joint disease: The most frequently reported manifestations in the above categories at or prior to index included increased anti-dsDNA antibody (74.6%), rash (49.2%), low complement (C3, C4, or CH50; 42.4%), arthritis (40.7%), leukopenia (30.5%), headache (18.6%), and alopecia (18.6%; Table 1).