title: [Epidemiological methods used in studies in the prevalence of Tourette syndrome].
abstract: Tourette syndrome (TS) prevalence was studied since the early 80-ies. Its clinical course is characterised by co-occurrence of motor and vocal tics. Results of previous epidemiological studies were surprisingly divergent: the prevalence varied from 0.5 to 115 cases per 10,000 population. The disease previously recognised as extremely rare and severe is now considered as quite common, with often moderate course. Selected methods used in studies of TS prevalence and analysis of their possible impact on study results are presented. The studies were divided into 3 groups: studies of the hospitalised population, large-scale screenings and studies involving school population, basing on characteristic and size of population, methods of selection of subjects, diagnostic and screening methods used. Studies of the hospitalised population involved patients with most severe symptoms, in different age groups, different methods of final diagnosis confirmation were used. TS prevalence varied from 0.5 up to 15 cases per 10,000 population. Procedures used in large-scale screening studies made possible the elimination of potential selection bias. Large populations were studied using transparent and repetitive confirmation of diagnoses. Their validity was additionally checked in parallel validity studies. TS prevalence was in the range 4.3 to 10 cases per 10,000 population. The highest TS prevalence was obtained in studies involving schoolchildren. Data were gathered from multiple sources: from parents, teachers and children, as well as from classroom observation. Diagnoses were made by experienced clinicians. TS prevalence obtained in school population studies was between 36.2 up to 115 per 10,000 population.
authors.affiliation: Zakładu Epidemiologii Państwowego Zakładu Higieny w Warszawie. pstefanoff@pzh.gov.pl
authors.forename: Paweł
authors.initials: P
authors.lastname: Stefanoff
authors.forename: Jacek
authors.initials: J
authors.lastname: Mazurek
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology; D004812:Epidemiologic Methods; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D008403:Mass Screening / Q000379:methods; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis / Q000453:epidemiology; D010808:Physical Examination / Q000379:methods; D011159:Population Surveillance; D015995:Prevalence; D012107:Research Design; D012574:Schools / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D005879:Tourette Syndrome / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology*