All cases of RF (n = 8/1390) were in females, yielding gender-specific prevalence estimates of 1.0 [0.5–2.1]% (n = 780) for females and 0.0 [0.0–0.5]% (n = 610) for males (p = 0.011, Fisher's exact test, not significant when corrected for multiple comparisons among all conditions in Table 2). Participants with OCD onset at 8 years or younger had a higher prevalence of tic disorders compared with those with later onset (30.0 [24.5–36.1]% vs. 18.7 [15.3–22.5]%, n = 687, p = 0.001 by Fisher's exact test), but no difference in prevalence of any immune-related comorbidity. Similarly, there was no significant effect of gender, ethnicity (Caucasian vs. other), or comorbid tic disorder on prevalence of encephalitis or meningitis, frequent ear/throat infections, scarlet fever, RF, RA, asthma, psoriasis, IBD, or the presence of at least one comorbidity.
