title: Observation period effects on estimation of systemic lupus erythematosus incidence and prevalence in Quebec.
abstract: OBJECTIVE
  To determine how duration of observation affects estimation of incidence and prevalence of systemic lupus erythematosus (SLE).
  
  
  METHODS
  SLE incidence and prevalence estimates from data periods as brief as 3 years (2001-2003) were compared to estimates from a 15-year period (1989-2003).
  
  
  RESULTS
  The 15-year period incidence was 5.6/100,000 (95% CI 5.0-6.1) and the prevalence was 59.1/100,000 (95% CI 57.4-60.8). When a 3-year period was used, incidence was overestimated by 238.1% and prevalence underestimated by 66.0%.
  
  
  CONCLUSIONS
  SLE incidence and prevalence estimates vary considerably according to the observation period; more than 5 years of data is likely required.
authors.affiliation: Division of Clinical Epidemiology, McGill University Health Centre (MUHC), Montreal, Quebec, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: Ng
authors.forename: Sasha
authors.initials: S
authors.lastname: Bernatsky
authors.forename: Elham
authors.initials: E
authors.lastname: Rahme
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008180:Lupus Erythematosus, Systemic / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011792:Quebec / Q000453:epidemiology; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult
keywords: INCIDENCE; PREVALENCE; SYSTEMIC LUPUS ERYTHEMATOSUS