Moderators of the association between attention-deficit/hyperactivity disorder and exposure to anaesthesia and surgery in children.

Background: Children's exposure to anaesthesia has been associated with risk of developing attention-deficit/hyperactivity disorder (ADHD). The goal of this study was to determine if selected patient characteristics moderate the association between exposure to anaesthesia and ADHD.

Methods: In a cohort of children born in between 2006 and 2012, exposure to anaesthesia before the age of 5 yr was categorised into unexposed, singly, or multiply exposed.