Decreases in anti-double-stranded DNA levels are associated with concurrent flares in patients with systemic lupus erythematosus

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Abstract
Objective To determine the degree to which changes in anti–double‐stranded DNA (anti‐dsDNA), as determined by Crithidia and enzyme‐linked immunosorbent assays (ELISAs), precede or coincide with changes in systemic lupus erythematosus (SLE) activity, as measured by 5 clinical indices, the physician's global assessment (PGA), modified SLE Disease Activity Index (M‐SLEDAI), modified Lupus Activity Index (M‐LAI), Systemic Lupus Activity Measure (SLAM), and the modified British Isles Lupus Assessment Group (M‐BILAG). Methods Disease activity and anti‐dsDNA were measured monthly in 53 SLE patients who were followed up for 1 year. Lupus flare was defined as an increase in PGA of ≥1.0, M‐SLEDAI ≥3, M‐LAI ≥0.1, SLAM ≥3, and M‐BILAG ≥4 within a 1‐month period. Flare rates were calculated for groups, which were defined by “previous” (1 month prior to the flare) or “concurrent” (at the time of the flare) changes in anti‐dsDNA. Logistic regression models were used to determine the significance of the association between recent changes in anti‐dsDNA and flare, controlling for the prednisone dosage. Results Flares occurred at 12% of visits, based on the PGA measure of disease activity. Using the other indices, flare rates were 19% (M‐SLEDAI), 25% (M‐LAI), 13% (SLAM), and 12% (M‐BILAG). A concurrent decrease in anti‐dsDNA (ELISA) was associated with significantly higher flare rates based on PGA (18 of 84, 21%; P = 0.0014), M‐SLEDAI (27 of 89, 30%; P = 0.0019), M‐LAI (37 of 89, 42%; P = 0.0001), and M‐BILAG (19 of 89, 21%; P = 0.0264) scores. Flare rates were also significantly higher after a previous increase in anti‐dsDNA (ELISA) based on M‐SLEDAI (26 of 93, 30%; P = 0.0022) and M‐LAI (34 of 93, 37%; P = 0.0117) scores. Flare rates tended to be lowest when there was a concurrent increase in anti‐dsDNA (ELISA). Analysis of specific organ systems showed that a concurrent decrease in anti‐dsDNA (ELISA) was significantly associated with increases in renal disease activity. Similar results were obtained using the Crithidia assay. Conclusion A previous increase in anti‐dsDNA levels occurred before SLE flares, as measured by the M‐SLEDAI and M‐LAI only. However, during lupus flares, including the subset of renal flares, anti‐dsDNA levels frequently decreased. We hypothesize that this decrease in anti‐dsDNA represents deposition in tissue at the time of flare.