censusADHD Study: An Australian-wide medication-based recruitment study for Attention-Deficit/Hyperactivity Disorder

Abstract

Objective: Attention-Deficit/Hyperactivity Disorder (ADHD) affects around 5% of children and is characterised by a persistent pattern of problems with focussing or maintaining attention and/or hyperactivity-impulsivity. The censusADHD Study is a richly-phenotyped nation-wide cohort of Australian children with ADHD that aims to examine the impact of children’s attention and behavioural problems on the financial, emotional, and psychological wellbeing of parents and caregivers. Methods: Families of potential ADHD cases aged between 6 and 11 years old were identified using Pharmaceutical Benefits Scheme (PBS) prescription records for ADHD medications held by the Department of Human Services and sent a study information letter. Data were collected from 1,574 primary caregivers via online survey from June-September 2015, including the behavioural profile of the index child, the child’s medication use and experiences with side-effects, and the impact of the child’s behaviour on the caregiver. Approximately 81% of caregivers also consented to record linkage of the child’s PBS and Medicare Benefits Schedule claims.Results: Boys were diagnosed with ADHD earlier (P=0.021) and more likely to present as the combined and predominantly hyperactive subtypes (P=0.001). Boys were also at higher risk for experiencing a school suspension (P<0.001) or expulsion (P=0.043). Overall, children presenting as the combined subtype had higher rates of psychiatric comorbidities (P<0.001). Finally, prescription costs for each family and the PBS significantly increased in the year following ADHD diagnosis (P<0.001).Conclusion: Research examining the psychosocial and financial impact of ADHD on Australian children and their families in population-representative cohorts is needed. Our findings demonstrate the importance of examining both gender and ADHD subtype presentation in future studies.