PT - JOURNAL ARTICLE AU - Martino, Davide AU - Schrag, Anette AU - Anastasiou, Zacharias AU - Apter, Alan AU - Benaroya-Milstein, Noa AU - Buttiglione, Maura AU - Cardona, Francesco AU - Creti, Roberta AU - Efstratiou, Androulla AU - Hedderly, Tammy AU - Heyman, Isobel AU - Huyser, Chaim AU - Madruga, Marcos AU - Mir, Pablo AU - Morer, Astrid AU - Mol Debes, Nanette AU - Moll, Natalie AU - Müller, Norbert AU - Müller-Vahl, Kirsten AU - Munchau, Alexander AU - Nagy, Peter AU - Plessen, Kerstin Jessica AU - Porcelli, Cesare AU - Rizzo, Renata AU - Roessner, Veit AU - Schnell, Jaana AU - Schwarz, Markus AU - Skov, Liselotte AU - Steinberg, Tamar AU - Tarnok, Zsanett AU - Walitza, Susanne AU - Dietrich, Andrea AU - Hoekstra, Pieter J. AU - , TI - Association of Group A <em>Streptococcus</em> Exposure and Exacerbations of Chronic Tic Disorders AID - 10.1212/WNL.0000000000011610 DP - 2021 Mar 23 TA - Neurology PG - e1680--e1693 VI - 96 IP - 12 4099 - http://n.neurology.org/content/96/12/e1680.short 4100 - http://n.neurology.org/content/96/12/e1680.full SO - Neurology2021 Mar 23; 96 AB - Objective To examine prospectively the association between group A Streptococcus (GAS) pharyngeal exposures and exacerbations of tics in a large multicenter population of youth with chronic tic disorders (CTD) across Europe.Methods We followed up 715 children with CTD (age 10.7 ± 2.8 years, 76.8% boys), recruited by 16 specialist clinics from 9 countries, and followed up for 16 months on average. Tic, obsessive-compulsive symptom (OCS), and attention-deficit/hyperactivity disorder (ADHD) severity was assessed during 4-monthly study visits and telephone interviews. GAS exposures were analyzed using 4 possible combinations of measures based on pharyngeal swab and serologic testing. The associations between GAS exposures and tic exacerbations or changes of tic, OC, and ADHD symptom severity were measured, respectively, using multivariate logistic regression plus multiple failure time analyses and mixed effects linear regression.Results A total of 405 exacerbations occurred in 308 of 715 (43%) participants. The proportion of exacerbations temporally associated with GAS exposure ranged from 5.5% to 12.9%, depending on GAS exposure definition. We did not detect any significant association of any of the 4 GAS exposure definitions with tic exacerbations (odds ratios ranging between 1.006 and 1.235, all p values &gt;0.3). GAS exposures were associated with longitudinal changes of hyperactivity–impulsivity symptom severity ranging from 17% to 21%, depending on GAS exposure definition.Conclusions This study does not support GAS exposures as contributing factors for tic exacerbations in children with CTD. Specific workup or active management of GAS infections is unlikely to help modify the course of tics in CTD and is therefore not recommended.ADB=anti-DNase B; ADHD=attention-deficit/hyperactivity disorder; ASOT=anti-streptolysin O; CTD=chronic tic disorders; CY-BOCS=Children's Yale-Brown Obsessive-Compulsive Scale; DSM-IV-TR=Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision; EMTICS=European Multicenter Tics in Children Study; GAS=group A Streptococcus; OCD=obsessive-compulsive disorder; OR=odds ratio; PANDAS=pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection; PANS=pediatric acute neuropsychiatric syndromes; SNAP-IV=Swanson, Nolan, and Pelham IV; TS=Tourette syndrome; YGTSS-TTS=Yale Global Tic Severity Scale–Total Tic Severity Score