title: Patterns of disease activity in systemic lupus erythematosus.
abstract: OBJECTIVE
  To describe patterns of systemic lupus (SLE) disease activity over time.
  
  
  METHODS
  Disease activity was measured in a prospective cohort of 204 consecutive SLE patients followed up quarterly for 2.0-7.5 years (911 person-years of followup). Physician's global assessment (PGA) and modified SLE Disease Activity Index (M-SLEDAI; omitting serology) scores were plotted against time for each patient. Definitions for disease activity patterns were developed by consensus using these plots, and the proportion of total follow-up time represented by each pattern was calculated.
  
  
  RESULTS
  Three patterns of SLE activity were apparent: relapsing-remitting (RR), chronic active (CA), and long quiescent (LQ). The CA pattern was the most frequent for both the PGA and M-SLEDAI, representing 58% and 40% of total person-years, respectively. The least common pattern was LQ (PGA 16%, M-SLEDAI 25%), while the RR pattern was intermediate in frequency (PGA 26%, M-SLEDAI 35%). Average disease activity during RR periods tended to be mild, while that during CA periods was more likely to be moderately severe. The most common discrepancy between instruments was that the PGA depicted CA when the M-SLEDAI showed an RR pattern. The M-SLEDAI did not appear to capture mild degrees of activity.
  
  
  CONCLUSIONS
  SLE activity was readily classified into 1 of 3 patterns: RR, CA, or LQ. The CA pattern was most common, suggesting that significant morbidity may arise from persistent disease activity. These findings may have important implications regarding the choice of outcome measures in SLE clinical trials, since comparison of flare rates may not account for chronic disease activity.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: S G
authors.initials: SG
authors.lastname: Barr
authors.forename: A
authors.initials: A
authors.lastname: Zonana-Nacach
authors.forename: L S
authors.initials: LS
authors.lastname: Magder
authors.forename: M
authors.initials: M
authors.lastname: Petri
mesh_terms: D000328:Adult; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index