BACKGROUND: Prevalence is a simple statement about the frequency of a disease in the population. For many medical conditions, including @entity4676 , there are true cases that have not been previously diagnosed due to problems of access to appropriate clinical services. Therefore, to obtain a trustworthy estimate of prevalence, it is necessary to go beyond cases identified in clinical settings and evaluate community samples. METHOD: We reviewed 11 community surveys in @entity1 with @entity4676 ( @entity4676 ) published since 2000. We also examined the frequency of co-occurring @entity146 conditions in community samples and large clinically-ascertained samples. RESULTS: Transient @entity1775 are relatively common affecting as many as 20% of school-age @entity1 . The 11 studies reviewed here offer a wide range of estimates from 2.6 to 38 per 1000 @entity1 for @entity4676 . Six studies provide estimates in a narrower range from 4.3 to 7.6 per 1000, but the confidence interval around this narrower range remains wide. Six studies provided results on chronic @entity1765 ranging from 3 to 50 per 1000 for @entity1765 and 2.5 to 9.4 per 1000 for @entity1765 . Community samples and large clinically-ascertained samples consistently show high rates of @entity71 , disruptive behavior and @entity148 in @entity1 with @entity4676 . CONCLUSIONS: The wide range of prevalence estimates for @entity4676 and chronic @entity1765 is likely due to differences in sample size and assessment methods. The best estimate of prevalence for @entity4676 in school-age @entity1 is likely to fall between 4 and 8 cases per 1000. Clinical assessment of @entity1 with chronic @entity1765 warrants examination of other problems such as @entity71 , disruptive behavior and @entity148 .

The Prevalence of @entity1765 and Clinical Characteristics in XXXX .

@entity1 :: ('9606', 'Species') :: ['children'] @entity1775 :: ('MESH:D020323', 'Disease') :: ['tics'] @entity146 :: ('MESH:D001523', 'Disease') :: ['psychiatric'] @entity1765 :: ('MESH:D013981', 'Disease') :: ['Chronic Vocal Tic Disorder', 'Chronic Motor Tic Disorder', 'tic disorders'] @entity71 :: ('MESH:D001289', 'Disease') :: ['ADHD'] @entity148 :: ('MESH:D001008', 'Disease') :: ['anxiety', 'anxiety disorders'] @entity4676 :: ('MESH:D005879', 'Disease') :: ['TS', 'Tourette syndrome']
@entity1 :: (9606,Species) :: ['Children']
