title: 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 <6) and serologically active (anti-dsDNA antibodies >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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: University College London, London, UK.
authors.forename: K P
authors.initials: KP
authors.lastname: Ng
authors.forename: J J
authors.initials: JJ
authors.lastname: Manson
authors.forename: A
authors.initials: A
authors.lastname: Rahman
authors.forename: D A
authors.initials: DA
authors.lastname: Isenberg
mesh_terms: D000328:Adult; D000368:Aged; D000974:Antibodies, Antinuclear / Q000097:blood / Q000276:immunology*; D015331:Cohort Studies; D004247:DNA / Q000276:immunology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000453:epidemiology / Q000276:immunology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009707:Nucleosomes / Q000276:immunology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies
chemical_list: D000974:Antibodies, Antinuclear; D009707:Nucleosomes; D004247:DNA