Results of univariate and multivariate logistic regressions are summarized in Table 6. In the unadjusted models, first-degree relatives of patients with CD (OR, 1.8; CI, 1.2-2.6) and subjects with symptoms of disease (OR, 2.1; CI, 1.6-2.7) carried a higher risk of CD. In the overall adjusted model (which included degree of relatedness, sex, and adults vs children), first-degree relatives carried a higher risk of CD than second-degree relatives (OR, 1.7; CI, 1.2-2.5). By contrast, female sex (OR, 1.0; CI, 0.7-1.3; P = .75), presence of symptoms (OR, 1.2; CI, 0.9-1.6; P = .25), and adult status (OR, 1.2; CI, 0.8-1.6; P = .34) did not reach statistical significance. Removal of the latter 3 factors did not significantly affect the model (likelihood ratio statistic, P = .50). A subanalysis including only nonrelatives of patients with CD revealed that the presence of symptoms significantly predicted CD positivity (OR, 2.1; CI, 1.6-2.7; P<.001); neither sex (OR, 1.0) nor age (OR, 1.0) attained significance. Compared with the South, 2 geographic regions had higher CD prevalence: the West (OR, 1.7; CI, 1.03-2.7) and the Northeast (OR, 1.6; CI, 1.1-2.4).