Feasibility and validity were demonstrated of an online case-control study using the prototype of recent-onset systemic lupus erythematosus.
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.
McAlindon
Timothy
T
Division of Rheumatology, Tufts-New England Medical Center, 750 Washington Street, Box 406, Boston, MA 02111, USA. tmcalindon@tufts-nemc.org
Wang
Jun
J
Formica
Margaret
M
Kay
Ashley
A
Tighiouart
Hocine
H
Chaisson
Christine
C
Fletcher
Jeremiah
J
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
D013449:Sulfonamides