This research project seeks to examine the patterns and costs of Pharmaceutical Benefits Scheme-subsidised opioid use, including extra-medical use, in the Australian population.
Professor Sallie Pearson
Centre for Big Data Research in Health, UNSW Australia
Ms Bianca Blanch
Faculty of Pharmacy, University of Sydney
The global increase in prescribed opioid use over the past 30 years has been well documented. In Australia, between 1992 and 2007, there was a 300% increase in the number of opioid prescriptions dispensed in the community. In 2012, 7.4 million opioid prescriptions were dispensed via the Pharmaceutical Benefits Scheme (PBS), costing the Australian government approximately $271 million. In the 20-year period 1992-2012, the Commonwealth of Australia subsidised over $2 billion in prescribed opioids, with oxycodone and morphine accounting for $1.1 billion. Europe and the United States have seen even larger increases in opioid dispensing than Australia. Despite the Australian government’s significant investment in these medicines, we know little about the way they are used in routine clinical care. Furthermore, few studies have examined person-level behaviours of people prescribed opioids, prescribing patterns, patterns of use, or the outcomes and costs associated with this use. In order to gain a comprehensive understanding of these issues, we have commenced a programme of research examining the patterns and costs of PBS- subsidised opioid use, including extra-medical use in the Australian population.
The overall objective of this research program is to evaluate the patterns and costs of opioid use in Australia. The specific aims are to:
- Estimate monthly and annual utilisation and costs of prescribed opioids, overall and according to individual opioid formulations and strengths.
- Examine patterns of opioid use including initiation of therapy, duration of treatment, concomitant use of opioids and other therapy.
- Examine patterns of extra-medical opioid use based on indicators including excess dosing, use of more than one opioid concomitantly, doctor/pharmacy shopping, and accelerated time to prescription refill.
This research program is based on two different cohorts of prescription opioid users:
Prevalent user cohort: comprising Australians dispensed at least one opioid. This is a national cohort of all persons (of any age) prescribed at least one opioid of interest in a given calendar year (with the first year of data being 2013). The cohort will provide contemporary information about the prevalence of monthly and annual prescribed opioid use across the Australian population, including data from under co-payment opioid prescriptions. Data will be updated annually.
Incident user cohort: comprising Australians commencing new opioid therapy. This is a national cohort focusing on persons dispensed at least one opioid in the period July 1 2009 to December 31 2013. Our observation period was chosen as the Department of Human Services holds PBS data for a period of only four years and six months. The dataset is updated daily and when each additional day is added, the earliest date in the dataset is deleted. Therefore, our exact study period is dependent on the date of extraction. This cohort will be used to examine patterns of prescribed opioid use, including extra-medical use. Inclusion criteria are as follows: 1) opioid naïve for at least 3 months prior to the index prescription; 2) aged ≥18 years at the index prescription. We chose a 3-month wash-out period for cohort inclusion because it was considered sufficient time to ensure that any new, index prescriptions reflected a new “course” of treatment for a new or recurrent indication. It is possible that some individuals will receive a new prescription under this definition for an indication for which they have been treated previously. However, we will also undertake sensitivity analyses by extending the period of non-use to six months. This cohort will also be updated annually.
We will use best-practice pharmacoepidemiological methods to explore prescribed opioid medicines use in the two cohorts including:
- Utilisation and costs: we estimate the monthly and annual prevalence and costs of opioid use overall and according to individual opioid formulations and strengths.
- Patterns of opioid use: we will examine patterns of use in the following ways:
- Median duration of opioid treatment
- Dose escalation
- Concomitant opioid and other concomitant medicines use
- Extra-medical use: Indicators of extra-medical opioid use – we will adopt measures of extra-medical use described previously in the literature and report on the rates of these patterns of extra-medical use examining:
- Excess dosing
- Concomitant opioid use
- Doctor shopping
- Pharmacy shopping
- Accelerated prescription refill
We may restrict some of our analyses to concession card-holding populations only as not all opioid medicines of interest are above the general beneficiary co-payment amount. Other medicines of interest including benzodiazepines and psychotropic medicines such as antidepressants, antipsychotics and central nervous system stimulants, also fall below the general beneficiary co-payment. We will also undertake analyses with and without persons dispensed cancer medicines to establish how the inclusion of cancer patients (who generally receive significantly higher opioid doses than non-cancer patients) impacts on our estimates.
We have received full ethics approval for this study as well as all data feeds. We are currently in the process of planning and undertaking the various analyses outlined in the aims.
- Degenhardt L, Blanch B, Gisev N, Larance B, Pearson S. The POPPY research programme protocol: investigating opioid utilisation, costs and patterns of extra-medical use in Australia. BMJ Open 2015;5:e007030 doi:10.1136/bmjopen-2014-007030.
- Gisev N, Pearson SA, Blanch B, Larance B, Dobbins T, Larney S, Degenhardt L. (2016). Initiation of strong prescription opioids in Australia: cohort characteristics and factors associated with the type of opioid initiated. British Journal of Clinical Pharmacology. 82:1123-33.
- Blanch B, Degenhardt L, Buckley NA, Gisev N, Dobbins T, Karanges E, Larance B, Larney S, Pearson SA. Prescription opioid access patterns and factors associated with increasing numbers of prescribers, pharmacies and dispensings: an observational study using pharmaceutical claims. Pain Medicine. Published online 10th April 2017.
- Gisev N, Karanges E, Pearson SA, Buckley N, Larance B, Larney S, Dobbins T, Blanch B, Degenhardt L. To what extent do data from pharmaceutical claims under-estimate opioid analgesic utilisation in Australia? Pharmacoepidemiology and Drug Safety. Published online 19th October 2017.
- Gisev N, Pearson SA, Blanch B, Larance B, Dobbins T, Larney S, Degenhardt L. Initiation of strong prescription opioids in Australia: cohort characteristics and factors associated with the type of opioid initiated. Presented at the 32nd International Conference on Pharmacoepidemiology & Therapeutic Risk Management. 25-28 August 2016. Dublin, Ireland.
- Blanch B, Degenhardt L, Gisev N, Dobbins T, Larance B, Larney S, Pearson SA. Prescription opioid access patterns in Australia: A national observational cohort study. Presented at the 32nd International Conference on Pharmacoepidemiology & Therapeutic Risk Management. 25-28 August 2016. Dublin, Ireland.
- Gisev N, Pearson SA, Blanch B, Larance B, Dobbins T, Larney S, Degenhardt L. Characteristics of a population-based cohort initiating strong prescription opioids in Australia and factors associated with the type of opioid initiated. Presented at the National Drug and Alcohol Research Centre 2016 Annual Symposium. 12 September 2016. Sydney, Australia.
- Gisev N, Pearson SA, Karanges EA, Larance B, Buckley NA, Larney S, Dobbins T, Blanch B, Degenhardt L. To what extent do data from pharmaceutical claims under-estimate opioid analgesic utilisation in Australia? Accepted for presentation at the 33rd International Conference on Pharmacoepidemiology & Therapeutic Risk Management. 26-30 August 2017. Montreal, Canada.
- Gisev N, Pearson SA, Karanges EA, Larance B, Buckley NA, Larney S, Dobbins T, Blanch B, Degenhardt L. To what extent do data from pharmaceutical claims under-estimate opioid analgesic utilisation in Australia? Accepted for presentation at the National Drug and Alcohol Research Centre 2017 Annual Symposium. 3-4 October 2017. Sydney, Australia.
- Gisev N, Pearson SA, Karanges EA, Larance B, Buckley NA, Larney S, Dobbins T, Blanch B, Degenhardt L. Quantifying the extent that data from PBS/RPBS claims under-estimate opioid analgesic utilisation in Australia. Accepted for presentation at the 10th Asian Conference on Pharmacoepidemiology. 29-31 October 2017. Brisbane, Australia.
The rate of pharmaceutical opioid use is increasing, both nationally and internationally. However, the actual extent of the problem is currently unknown. The study will examine the prevalent use of opioids in Australia and estimate the total cost incurred by the Australian Government to supply opioids in the community. Furthermore, by tracking a cohort of incident opioid users, this study will be the first large-scale and nationally-representative study conducted in Australia to rigorously examine patterns of opioid use. Previously, PBS opioid dispensing data has only been released in aggregated formats, preventing detailed person-level analyses to be undertaken. Overall, this research has the capability to contribute significantly to pharmaceutical policy both within Australia and globally.