Drug use in children: cohort study in three European countries.

To provide an overview of drug use in children in three European countries. Retrospective cohort study, 2000-5. Primary care research databases in the Netherlands (IPCI), United Kingdom (IMS-DA), and Italy (Pedianet). 675 868 children aged up to 14 (Italy) or 18 (UK and Netherlands). Prevalence of use per year calculated by drug class (anatomical and therapeutic). Prevalence of "recurrent/chronic" use (three or more prescriptions a year) and "non-recurrent" or "acute" use (less than three prescriptions a year) within each therapeutic class. Descriptions of the top five most commonly used drugs evaluated for off label status within each anatomical class. Three levels of drug use could be distinguished in the study population: high (>10/100 children per year), moderate (1-10/100 children per year), and low (