Author Contributions: Drs Halvorsen, Bjertness, and Lien had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Halvorsen and Bjertness. Acquisition of data: Bjertness. Analysis and interpretation of data: Halvorsen, Vleugels, and Lien. Drafting of the manuscript: Halvorsen and Vleugels. Critical revision of the manuscript for important intellectual content: Vleugels, Bjertness, and Lien. Statistical analysis: Halvorsen. Obtained funding: Halvorsen and Bjertness. Administrative, technical, and material support: Halvorsen and Bjertness. Study supervision: Vleugels, Bjertness, and Lien.
Financial Disclosure: None reported.
Funding/Support: This study was supported in part by The University of Oslo and Norwegian Institute of Public Health, The Regional Center for Child and Adolescent Mental Health, Eastern and Southern Norway; The University of Oslo and Norwegian Institute of Public Health for Planning, Conducting and Funding of Youth 2004.
Role of the Sponsors: The sponsors had no role in the design and conduct of the study; in the collection, analysis, and interpretation of data; or in the preparation, review, or approval of the manuscript.
Additional Contributions: Florence Dalgard, MD, PhD, helped collect data and reviewed the article.