Reader Response: Lack of Association of Group A Streptococcal Infections and Onset of Tics
“Schrag et al. reported that Group A streptococcal (GAS) exposure is unrelated to tics in children at risk for tic disorders.1 The critical limitations of this study are that only children with genetic risks for tics were studied and information about risk for autoimmunity, infection susceptibility, and antibiotics use are absent.1 The EMTICS home page states that many patients refused to participate when told that antibiotic use would be limited. This would introduce a negative selection bias against families who perceive themselves as high risk and patients procuring antibiotics outside the trial.2“
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