• Open Access

Response to Calver et al. on the WA regulatory scheme for stimulants


Correspondence to:
Dr Margaret Stevens, Department of Health, 189 Royal Street, East Perth, Western Australia 6004. Fax: (08) 9222 2232; e-mail: margaret.stevens@health.wa.gov.au

Calver et al.,1 in their analysis of the use of stimulants in Western Australia, have concluded that “the majority of Attention Deficit Hyperactivity Disorder (ADHD) patients use their medication as prescribed”. The authors have attributed discrepancies between the notified and dispensed doses of stimulants prescribed for the treatment of ADHD to misuse and diversion. They are critical of the Western Australia Stimulants Regulatory Scheme for failing to prevent over-prescribing and call for the Department of Health to “act pre-emptively and decisively in taking stronger regulatory action”.

Before leaping to change, it is useful to consider all possible causes of the observed discrepancy, whether the data support the conclusions, and the functionality of the existing regulatory scheme. It is also important to bear in mind that the data analysed were from the first 17 months of a new regulatory system and so reflect the transition from an unregulated to a regulated environment.

There are three possible causes of the observed discrepancy. The first is poor compliance by prescribers with the requirement to renotify dose increases. The regulatory system requires notification at the initiation of prescribing and renotification at certain dose increments. Failure to renotify a dose increase will cause a dose discrepancy.

The second cause also relates to prescribing behaviour, whereby prescriptions are dispensed before the full amount of the previous prescription is consumed. This is exacerbated if the total amount of medicine prescribed is rounded to whole packs. Early dispensing has been significantly controlled by regulations introduced in 2006, which require specification of the date of dispensing on repeat prescriptions.

The third potential cause of the discrepancy is intentional over-prescribing related to abuse or diversion of stimulants, as when prescribers accede to patient requests for additional medicine or patients doctor-shop.

It is not possible to quantify the individual contribution of these three causes to the observed discrepancy. Using the minimum discrepancy estimate model, Calver et al. estimated that 5.4% of patients accessed doses greater than those notified. This excess comprises that from lack of renotification plus intentional over-prescribing and is consistent with our experience in managing the regulatory system.

The maximum discrepancy estimate is an ‘ideal’ model, which makes no allowance for the reality of system design or the known practices of prescribers, and so is an inappropriate comparative model. Quantification of over-prescribing determined from the model using the maximum discrepancy estimate is not consistent with our experience.

The notification system is designed to detect deliberate excessive access to stimulant medication. The requirement for immediate notification of stimulant treatment reduces the opportunity for patients to doctor-shop and for non-authorised doctors to prescribe stimulants. Monitoring of dispensed medicine against that notified for individual patients allows the identification of prescribing outside the regulatory guidelines. The notification system is less able to detect variation in dose within the regulatory guidelines, however small changes at these dosing levels are within the range of accepted clinical practice.

As with many regulatory systems, the regulatory scheme depends on the co-operation of the health professionals who supply data for monitoring and whose clinical practice is curtailed by the regulatory requirements. Imposition of significantly greater requirements for reporting and restrictions on prescribing can only be justified if supported by data and where there is a clear assessment that the benefits justify the costs.

Calver et al. have tackled a difficult subject in an area where the evidence base is limited and data hard to interpret. Their focus on diversion is an understandable reflection of community concerns, but is not substantiated by the present analysis. The Stimulants Regulatory Scheme is under regular review and the Department of Health welcomes meaningful research which contributes to improved regulatory approaches.