We thank Dr Stevens for her comments1 on our article, ‘Prescribed stimulant use by Western Australians with Attention Deficit Hyperactivity Disorder (ADHD): does amount dispensed exceed the expected authorised use?'.2 While we welcome Dr Stevens' contribution, we feel a response to the comments raised is needed to ensure that the impartiality of the original article is not diminished.
The primary purpose of our study was to determine if the WA Stimulant Regulatory Guidelines and regulatory system, at the time, were adequate to detect whether people with ADHD received prescribed stimulants surplus to clinical requirement. Whatever the methodological limitations of our study, they stemmed from inadequacies in the Guidelines, which Dr Stevens, as Chief Medical Adviser for the WA Department of Health (WADoH), can improve. Our independent, non-commissioned analysis was the first to be performed on data collected by the WADoH following the introduction of the new regulatory guidelines in August 2003 (and to our knowledge the only published and peer-reviewed results on the accrual of stimulant medication in the State). Hence, our work represents a baseline analysis of a new scheme, which may have improved since its inception.
We also respectfully disagree with Dr Stevens' comment that our article focuses on stimulant diversion. Indeed, we provided other possible explanations why people with ADHD may accrue excess amounts of stimulants, which Dr Stevens has repeated in her own response. The section of our discussion that outlines the possible explanations begins with the statement: “Interpreting these results is difficult, because patients may acquire excess medication throughout the course of a year for many reasons.” (p537)
Dr Stevens supports the 5.4% minimum prevalence estimate generated using the minimum discrepancy model, which was included in our analysis at the WADoH's request, despite several methodological limitations that attenuated the effect size, as discussed in our article. However, Dr Stevens asserts that the maximum discrepancy model is an “inappropriate comparative model”. We argue that the assumptions of the maximum discrepancy model are no more extreme than those that define the minimal discrepancy model; they are simply at different ends of the estimation range, and the latter is not embedded within WADoH regulations. Further, we did not claim that one of the estimates (i.e. minimum or maximum) is more representative of the true nature of excess stimulant accrual. Rather, we explicitly stated that the true proportion lies somewhere between the minimum and maximum estimates, but it is impossible to produce a single precise estimate due to the limitations of the data in their baseline state (p534).
As researchers and health professionals, we have a responsibility to assist in improving the Guidelines so that independent and scientifically rigorous evaluations can be performed regularly. We believe it is our duty to shed light on any issues that potentially hinder progress, reduce public transparency, increase health care costs, and ultimately, compromise consumer safety. Our study identified some potential problems in the Guidelines in their original state, although we acknowledged in our discussion (p538) that some of these areas may have improved since our study. We encourage subsequent analyses to confirm the effectiveness of these changes compared with our baseline analysis of the original data. Dr Stevens' comment that some of the problems and suggestions we identified represented “imposition of significantly greater requirements for reporting” and should be ignored until supported by data, may be convenient, but it is ethically suboptimal. When it concerns drugs of addiction, there are some practices that would not be too onerous on prescribers, such as specifying a prescription repeat interval that resembles a patient's expected usage, which does not always happen.
While we have a shared vision with Dr Stevens and the WADoH of improving the safe use of stimulants for the treatment of ADHD, Dr Stevens' response to our article suggests we have a different view on how best this can be achieved. Establishing and maintaining an effective and consistent dialogue between health researchers, health officials and the public at large is integral to the solution. We encourage readers to revisit our original article and reach their own conclusions.