Introduction
Attention-deficit/hyperactivity disorder (ADHD) is a common pediatric disorder associated with a considerable economic burden. In Canada, the estimated prevalence of ADHD in school-aged children is 4.1%–5.0% (Brault and Lacourse 2012; Centre for ADHD Awareness Canada [CADDAC] 2011), with an estimated cost (based on USA data) to the Canadian economy of >2 billion C$ per year (CADDAC 2011). Guidelines recommend stimulants as first-line pharmacotherapy for ADHD (Canadian Attention Deficit Hyperactivity Disorder Resource Alliance [CADDRA] 2011); however, a considerable proportion of patients receiving stimulants change their regimen, owing to an inadequate response, dose-limiting side effects, comorbid disorders, or personal preferences (Arnold 2000; Stockl et al. 2003; Elvanse Prescribing Information 2014; Equasym Prescribing Information 2014).
Claims database studies from Canada and the USA have demonstrated that, among stimulant-treated children and adolescents with ADHD, the 1-year prevalence of medication switching or augmentation is 19%–23% (Ben Amor et al. 2014; Betts et al. 2014). Other approved therapies used in patients with ADHD include nonstimulants such as guanfacine extended release (GXR) and atomoxetine (ATX). Although not approved for the treatment of ADHD, clonidine and atypical antipsychotics (AAPs) are commonly used off-label in ADHD, especially when stimulants fail.
ADHD is the most common diagnosis associated with an AAP prescription in young people in the USA and Canada, despite not being indicated for this condition (Pathak et al. 2010; Pringsheim et al. 2011b; Sohn et al. 2016a). Furthermore, AAPs were identified as the most common psychotropic medication used to augment a stimulant in a study using medical claims data from children and adolescents with ADHD enrolled in Quebec's provincial health plan (Régie de l'assurance maladie du Québec [RAMQ]) between 2007 and 2012 (Ben Amor et al. 2014). The same study also found AAPs to be the second most common medication when switching from a stimulant (Ben Amor et al. 2014).
Although commonly prescribed in individuals with ADHD, AAPs do not address the core symptoms of the disorder (Tramontina et al. 2009; Zeni et al. 2009), but are generally used to treat comorbid oppositional and aggressive behavior (Aman et al. 2004; Armenteros et al. 2007; CADDRA 2011; Pringsheim et al. 2015). Furthermore,...
