Association between streptococcal infection and obsessive-compulsive disorder, Tourette's syndrome, and tic disorder.

OBJECTIVE Reports have suggested that streptococcal infection may be etiologically related to pediatric autoimmune neuropsychiatric disorders (PANDAS), but there are few good epidemiologic studies to support this theory. Using population-based data from a large West-Coast health maintenance organization, we assessed whether streptococcal infection was associated with increased risk for obsessive-compulsive disorder (OCD), Tourette's syndrome (TS), or tic disorder. METHODS This is a case-control study of children 4 to 13 years old receiving their first diagnosis of OCD, TS, or tic disorder between January 1992 and December 1999 at Group Health Cooperative outpatient facilities. Cases were matched to controls by birth date, gender, primary physician, and propensity to seek health care. RESULTS Patients with OCD, TS, or tic disorder were more likely than controls to have had prior streptococcal infection (OR: 2.22; 95% CI: 1.05, 4.69) in the 3 months before onset date. The risk was higher among children with multiple streptococcal infections within 12 months (OR: 3.10; 95% CI: 1.77, 8.96). Having multiple infections with group A beta-hemolytic streptococcus within a 12-month period was associated with an increased risk for TS (OR: 13.6; 95% CI: 1.93, 51.0). These associations did not change appreciably when limited to cases with a clear date of onset of symptoms or with tighter matching on health care behavior. CONCLUSION These findings lend epidemiologic evidence that PANDAS may arise as a result of a postinfectious autoimmune phenomenon induced by childhood streptococcal infection.