Association of antinucleosome antibodies with disease flare in serologically active clinically quiescent patients with systemic lupus erythematosus

Abstract

Objective To identify the prevalence of serologically active clinically quiescent (SACQ) patients in a cohort of 290 patients with systemic lupus erythematosus (SLE). We investigated if the presence of anti–double‐stranded DNA (anti‐dsDNA) or antinucleosome (anti‐NCS) antibodies during the SACQ period was associated with future flares. Methods SACQ patients defined as clinically inactive for 6 months (global British Isles Lupus Activity Group index [BILAG] scores 50 units/ml on at least 2 occasions by enzyme‐linked immunosorbent assay [ELISA]) were identified. Patient sera collected during the defined SACQ period were also tested for anti‐NCS antibodies (ELISA). We retrospectively reviewed patient clinical details and episodes of flare using the BILAG activity index. Results Twenty‐seven (9%) patients were SACQ. Seventeen (81%) patients experienced a flare (total of 91 flares, up to 12 flares per person) in the next 5 years. Median duration to first flare was 15 months (range 2–46). Time to first flare after SACQ period was significantly correlated with the presence of anti‐NCS (P = 0.0012), high anti‐NCS antibody titers (P = 0.0006), and anti‐dsDNA titers 5 times above the normal limit (P = 0.02). Patients with higher absolute anti‐NCS antibody titers showed a significant correlation with the number of flares (r = 0.57, P = 0.007). Conclusion A minority of patients with SLE are SACQ. The majority of these patients experience a flare in the next 5 years and close followup is recommended. Anti‐NCS antibodies may be a better predictor than anti‐dsDNA antibodies for future flares.