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

Attention-deficit/hyperactivity disorder affects over 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 nationwide cohort of Australian children with attention-deficit/hyperactivity disorder. The overarching aims of the study are to examine attention-deficit/hyperactivity disorder medication utilisation patterns and treatment response, the impact of children's attention and behavioural problems on caregivers, and costs related to attention-deficit/hyperactivity disorder.

Families of potential attention-deficit/hyperactivity disorder cases aged between 6 and 11 years were identified using Pharmaceutical Benefits Scheme prescription records for attention-deficit/hyperactivity disorder medications held by Services Australia and sent a study information letter. Data were collected from 1574 primary caregivers via online survey in 2015, including the behavioural profile of the 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 Pharmaceutical Benefits Scheme and Medicare Benefits Schedule claims to directly assess prescription dispensing history and health service usage to estimate costs to the family and Medicare health system.

Boys were diagnosed with attention-deficit/hyperactivity disorder earlier (p = 0.021), more likely to present as the combined and predominantly hyperactive subtypes (p = 0.001) and at higher risk of 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 Pharmaceutical Benefits Scheme significantly increased in the year following attention-deficit/hyperactivity disorder diagnosis (p < 0.001).

Research examining the psychosocial and financial impact of attention-deficit/hyperactivity disorder on Australian children and their families is needed. Our findings demonstrate the importance of examining both gender and attention-deficit/hyperactivity disorder subtype presentation in future studies.