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  • Lisdexamfetamine Review DUSC PRD 2023 09

Analysis of Pharmaceutical Benefits Scheme (PBS) and Repatriation PBS (R/PBS) listed medicines used in the management of attention deficit hyperactivity disorder, September 2023

Page last updated: 22 March 2024

Drug utilisation sub-committee (DUSC)

September 2023

Abstract

Purpose

To review the utilisation of the Pharmaceutical Benefits Scheme (PBS) and Repatriation PBS (R/PBS) listed medicines used in the management of attention deficit hyperactivity disorder (ADHD). This includes a predicted versus actual analysis of the first 24 months of R/PBS listing of lisdexamfetamine extended use, to allow use in adults with ADHD persisting from childhood, even if diagnosed after 18 years of age. Lisdexamfetamine was first R/PBS-listed for this indication on 1 February 2021.

Date of listing on the PBS

  • Dexamphetamine - 1 December 1973
  • Methylphenidate immediate release (IR) - 1 August 2005
  • Methylphenidate modified release (MR) (Concertaâ) - 1 April 2007
  • Methylphenidate modified release (MR) (Ritalin LAâ) - 1 April 2008
  • Atomoxetine - 1 July 2007 requiring authority approval. On 1 August 2014, the restriction was simplified and changed to streamlined authority
  • Lisdexamfetamine - 1 September 2015 requiring authority approval
  • Guanfacine – 1 September 2018 requiring streamlined authority approval

Subsidy of atomoxetine and guanfacine is limited to people diagnosed between the ages of 6 and 18 years of age inclusive.

Atomoxetine and guanfacine are subsidised for people unable to take dexamphetamine or methylphenidate due to specific circumstances set out in the PBS restriction. People need to have been diagnosed by a paediatrician or psychiatrist according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria.

Lisdexamfetamine and modified-release methylphenidate (Concertaâ) are for people requiring coverage over 12 hours. A shorter modified-release methylphenidate (Ritalin LAâ) is available for people requiring coverage over 8 hours.

To use modified-release methylphenidate, people need to have demonstrated a response to immediate-release methylphenidate with no emergence of adverse events.

Data Source / methodology

The analysis used data from the supplied prescriptions database maintained by the Department of Health and Aged Care, processed by Services Australia and Australian Bureau of Statistics (ABS) estimated residential population (ERP) at 31 December for the specific financial year.

Key Findings

Over the ten financial years period, 2013-14 to 2022-23:

  • The rate of growth of prescriptions and people across all age groups and genders being treated with R/PBS medicines for ADHD has risen.
  • The average annual growth rate of prescriptions since 2013-2014 is just under 18%. However, the growth rate has greatly accelerated since the 2019-20 financial year. The growth rate over the four financial years, 2019-20 to 2022-23, is just over 25%. This increase is due to an increased use of all ADHD medications with the highest increases found in the prescribing of guanfacine (which was PBS listed on 1 September 2018), and lisdexamfetamine (which had a restriction change allowing use in the >18 year old population without prior diagnosis on 1 February 2021).
  • The growth in the number of prevalent people treated with R/PBS medicines for ADHD has risen at a similar rate to prescription growth, with an overall growth of 28% from 2021-22 to 2022-23. When this cohort is broken down into above 18 year old (>18 year old), and 18 and under year old (≤18 year old), population groups the growth rate was 40%, and 20% respectively.
  • The medicine used by the most people, in terms of prevalence, is different for the two age groups. Since the February 2021 restriction change, lisdexamfetamine has become the most used medication for >18 year olds. Prior to the restriction change dexamfetamine was the most used medicine in this age group. In the ≤18 year old population, the modified-release formulation of methylphenidate (MPH-MR) has consistently been the highest used medication.
  • For initiating people, more males than females were treated across all age groups apart from the 13-18 year old and over 18 year old female cohort (since the 2020-21 financial year), when their initiating rates overtook male initiating rates.
  • In the 2022-23 financial year, 41% of initiating people over 18 years old were male and 59% were female.
  • In the 2022-23 financial year, 48% of prevalent people over 18 years old were male and 52% were female. This was the first time an analyses undertaken by DUSC of ADHD medicine utilisation that female prevalent numbers have been higher than males.
  • In the 2022-23 financial year, of all initiating people treated with R/PBS listed ADHD medicines:
    • children under 6 years old account for 4.1% of the treated population
    • children aged 6-12 years old account for 30.8% of the treated population
    • adolescents aged 13-18 years old account for 15.2% of the treated population
    • adults aged over 18 years old account for 49.9% of the treated population
      • In the 2019-20 financial year, prior to the lisdexamfetamine restriction change, this group accounted for 32.8% of all initiating people treated
  • In the 2022-23 financial year, of all prevalent people treated with R/PBS listed ADHD medicines:
    • children under 6 years old account for 1.7% of the treated population
    • children aged 6-12 years old account for 32.7% of the treated population
    • adolescents aged 13-18 account for 21% of the treated population
    • adults aged over 18 years account for 44.6% of the treated population
      • In the 2019-20 financial year, prior to the lisdexamfetamine restriction change, this group accounted for 33.4% of all prevalent people treated

An analysis of medicine use in 2022-23 shows that:

  • The majority of prescriptions were written by paediatricians or psychiatrists.
  • The initial prescription of methylphenidate, lisdexamfetamine and dexamfetamine for the treatment of ADHD is generally restricted to specialists in most Australian states and territories.
  • Rates of prescribing vary across states and territories. In the 2022-23 financial year, the rates of treatment in >6 year olds were highest in Tasmania (Tas) and Queensland (QLD) and lowest in the Northern Territory (NT), while rates in school-aged children (6-12 years old) were highest in Tas, and lowest in South Australia (SA). Rates of treatment for 13-18 year olds was highest in ACT and lowest in SA, while rates of treatment in adults were highest in Western Australia (WA) and the Australian Capital Territory (ACT), and lowest in Tas and the NT. The adult rates of prescribing were much higher in WA and the ACT compared to the other States and the NT.

Lisdexamfetamine:  

  • The restriction change of lisdexamfetamine in February 2021 has contributed towards an increase in the use of ADHD medicines.
  • Prior to the restriction change, in the 2019-20 financial year 10,195 prevalent people >18 years old were treated with lisdexamfetamine.
  • In the 2020-21 financial year, which included five months of the restriction change, 27,546 prevalent people >18 years old were treated with lisdexamfetamine.
  • The 2021-22 financial year was the first full year to incorporate the restriction change.
  • In this financial year, 59,308 prevalent people >18 years of age were treated with lisdexamfetamine.
  • In the first year of the lisdexamfetamine restriction change, the actual scripts dispensed were different than the amount predicted. In the second year, the actual scripts dispensed were different than the predicted amount.

Clonidine

This ADHD utilisation report examines the use of clonidine as a medication prescribed for ADHD. While definitive results are difficult to establish due to clonidine’s unrestricted listing (i.e. the indication for which it is prescribed is not specified), it is estimated that clonidine is being used as an ADHD medication across all age groups. There is a high level of confidence that clonidine is being prescribed for ≤18 years old for ADHD, as this age group would not usually be prescribed clonidine for other diseases / disorders.

Full Report