Tic disorders: administrative prevalence and co-occurrence with attention-deficit/hyperactivity disorder in a German community sample.

Coexistence of tics and attention-deficit/hyperactivity disorder (ADHD) has important clinical and scientific implications. Existing data on the co-occurrence of tic disorders, Tourette Syndrome (TS), and ADHD are largely derived from small-scale studies in selected samples and therefore heterogeneous. The Nordbaden project captures the complete outpatient claims data of more than 2.2 million persons, representing 82% of the regional population in 2003. Based upon the number of diagnosed cases of tic disorders, TS, and ADHD, we determined 12-months administrative prevalence rates as well as rates of co-occurrence. Both tic disorders and ADHD were diagnosed most often in the age group 7-12 years (any tic disorder: 0.8%; ADHD: 5.0%). With increasing age, the administrative prevalence difference in favor of males disappeared, with tic disorders being somewhat more frequently reported in females than males in the age groups above 30 years. The highest rate of ADHD co-occurring with tic disorders was found in adolescents (age 13-18 years, 15.1%). Tic disorders were observed in 2.3% of patients with ADHD. Administrative prevalence rates of tic disorders and TS were substantially lower compared to rates found in community-based epidemiological studies, suggesting that a large number of cases remain undetected and untreated under present conditions of routine outpatient care.