title: Feasibility and validity were demonstrated of an online case-control study using the prototype of recent-onset systemic lupus erythematosus.
abstract: OBJECTIVE
  To test the feasibility and validity of the online case-control study design through the empirical deployment of a prototype study of recent-onset systemic lupus erythematosus (SLE).
  
  
  METHODS
  We conducted an Internet-based case-control study of SLE during 2003-2005. The source population comprised Google users searching on medical key terms, solicited using sponsored links. Cases fulfilled a self-administered algorithm for SLE diagnosed within 5 years. A subset underwent confirmation by medical record review. Controls were matched to cases using a propensity score.
  
  
  RESULTS
  Four hundred and two cases and 693 control applicants finished the questionnaires, yielding 389 matched case-control pairs. Eighty-two percentage of the records documented a clinical diagnosis of SLE, and 61% documented >or=4 American College of Rheumatology criteria for SLE. Control applicants resembled Internet users, with the exceptions of comprising more women (86% vs. 52%) and fewer minority individuals (e.g., 5% vs. 9% for African-Americans). There was a broad representation of clinical manifestations. SLE was associated with miscarriage (odds ratio [OR]=3.0, 95% confidence interval [CI]=2.0-4.7), allergy to sulfonamides (OR=2.2, CI=1.5-3.2), hives (OR=1.9, CI=1.4-2.5), and shingles (OR=2.3, CI=1.4-3.7).
  
  
  CONCLUSIONS
  It is possible to perform case-control studies over the Internet using an internally valid design, obtain reliable information from participants, and confirm established associations.
authors.affiliation: Division of Rheumatology, Tufts-New England Medical Center, 750 Washington Street, Box 406, Boston, MA 02111, USA. tmcalindon@tufts-nemc.org
authors.forename: Timothy
authors.initials: T
authors.lastname: McAlindon
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Margaret
authors.initials: M
authors.lastname: Formica
authors.forename: Ashley
authors.initials: A
authors.lastname: Kay
authors.forename: Hocine
authors.initials: H
authors.lastname: Tighiouart
authors.forename: Christine
authors.initials: C
authors.lastname: Chaisson
authors.forename: Jeremiah
authors.initials: J
authors.lastname: Fletcher
mesh_terms: D000022:Abortion, Spontaneous; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D035061:Control Groups; D004342:Drug Hypersensitivity / Q000150:complications; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000150:complications; D020407:Internet; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D013449:Sulfonamides; D011795:Surveys and Questionnaires
chemical_list: D013449:Sulfonamides