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Large increase in stimulant use for ADHD in Australia: new study

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JANUARY 27, 2011

Large increase in stimulant use for ADHD in Australia: new study

A new study has shown that between 2002 and 2009, dispensing of

stimulant medication in Australia—the majority of which is thought to be for the treatment of Attention Deficit Hyperactivity Disorder (ADHD)—has increased considerably.

The study, Australian national trends in stimulant dispensing: 2002-09, published in the Early Online edition of the Australian and New Zealand Journal of Psychiatry (ANZJP), used data from the Department of Health and Ageing to report trends in dispensed stimulant prescriptions between 2002 and 2009 by gender and age.

The drugs examined were dexamphetamine, methylphenidate (brand names: Ritalin and Concerta) and modafinil (brand name: Modavigil).

According to the study, between 2002 and 2009:

• there was an 87 per cent increase in stimulant dispensing in Australia • dexamphetamine remained the most commonly dispensed stimulant, though prescriptions fell by 13 per cent • the increase in stimulant dispensing was attributable to a 300 per cent increase in dispensed

methylphenidate following inclusion of the short-acting preparations on the Pharmaceutical Benefits Scheme (PBS) from 2005 and longer acting preparations from 2007 • dispensing of stimulant prescriptions peaked at 10-14 years of age • the use of stimulants was approximately five times greater in men than in women, although the Australian rate of prevalence of ADHD is 2.45 times greater in men than women.

In seeking to explain the 300 per cent increase in methylphenidate dispensing, the authors note that:

Although the most likely explanation for the increase ... was government subsidy [through the PBS], increased prescribing for stimulants has also been reported in North America and Europe. We

conjecture that this may be due to a number of factors including studies showing the effectiveness of stimulants for ADHD treatment, increased public awareness of ADHD, societal changes (for example children living in smaller housing, greater expectations of children to remain at school) and the influence of marketing by pharmaceutical companies. The authors also hypothesise that the peaking of stimulant prescription at 10-14 years of age reflects changing expectations placed upon children at school, arguing that the increase coincided with ‘increasing cognitive demands in the school environment and increasing expectations from parents, teachers and perhaps the students themselves’.

A point worth highlighting is that increases in dispensing of stimulants have tended to be greater in some Australian jurisdictions than in others. As the authors note, studies have reported increased use of stimulants in children and in adults in Western Australia (WA) and New South Wales (NSW), while other states such as South Australia have shown no consistent change.

In a 2004 Parliamentary Library study, I examined the differences between Federal electorates in dispensing of dexamphetamine through the PBS and found considerable variation both across and within jurisdictions, with WA electorates accounting for the top 14 electorates for prescription of ADHD medication in Australia. I also found that the number of PBS dexamphetamine prescriptions in Western Australia in 2003 was around three and a half times higher per 1000 population than the Australian average and more than 12 times higher than the jurisdiction with the lowest number of prescriptions, the Northern Territory.

The ANZJP study does not provide jurisdictional comparisons. However, such comparisons can be made using PBS data available from the Medicare Australia website. The graph below shows all PBS prescriptions for stimulants (dexamphetamine, methylphenidate and modafinil) between 2002-03 and 2009-2010.

PBS prescriptions dispensed for stimulant medication, states and territories, 2002-03 to 2009-10

Source: Medicare Australia, PBS statistics

In summary, the PBS data shows that:

• nationally, stimulant prescriptions increased by 92 per cent (250 851 to 480 930) betwen 2002-03 and 2009-10 • very large increases were recorded in NSW (181 per cent; 62 526 to 175 646), Victoria (148 per cent; 32 984 to 81 781), Queensland (163 per cent; 36 638 to 96 196), the Australian

Capital Territory (179 per cent; 3 236 to 9 036) and the Northern Territory (261 per cent; 745 to 2689) • smaller increases were recorded in Tasmania (60 per cent; 9129 to 14 630) and SA (13 per cent; 19 667 to 22 245) • prescriptions in WA fell from 85 926 in 2002-03 to 64 431 in 2006-07 before increasing

again to 78 707 in 2009-10 (an overall decrease of 8 per cent)—possibly reflecting concerns expresed earlier in the decade about the rapid growth in stimulant use in that state • prescriptions in all jurisdictions had begun to decline, before increasing (in some cases, rapidly) around 2004‐05—that is, around the time that methylphenidate became available 

through the PBS. 

It should be noted that the above figures are not directly comparable with those in the ANZJP study because, unlike the latter, they do not include an estimate of non-PBS stimulant dispensing and provide only the total number of prescriptions (rather than standardisation using the defined daily

dose per 1000 population per day). Nevertheless, they do provide a broad indication of the rates of increase across the states and territories.

So, to what extent is evidence of rapid increases in stimulant prescriptin a matter for concern? The authors of the ANZJP study makes the point that 'psychosocial interventions

are the first line treatment for ADHD' and that 'pharmacotherapy should be reserved for those individuals with more severe symptoms or impairment, or for those individuals with moderate impairment who have not responded to psychosocial interventions'. As such, they conclude that 'further research is required to determine if the increase in stimulant dispensing in Australia is clinically appropriate'.

A further conclusion could be that increases in stimulant dispensing need to be seen in the context of the relatively easy and affordable access to PBS medicines compared with services providing psychosocial interventions. As I argued in the 2004 Parliamentary Library study (in relation to the large increases in stimulant use in WA), 'it may be the case that decisions related to treatment of ADHD are as likely to be based on access to an appropriate range of health services and treatment options as they are to be based on evidence'.

Draft guidelines for the treatment of ADHD were released by the Royal Australasian College of Physicians (RACP) and National Health and Medical Research Council (NHMRC) in late 2009. These were then to be formally considered by the Council of the NHMRC 'after an alleged conflict of

interest investigation into a US-based researcher is completed'. The final version of the guidelines is yet to be released.

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Posted by Luke Buckmaster