NSW researchers have quantified – for the first time – that data based on PBS/RPBS claims underestimates total prescription opioid use
Researchers from the National Drug and Alcohol Research (NDARC) at the University of NSW have attempted to quantify actual opioid use in Australia, arguing that estimates based on pharmaceutical claims alone are “problematic”, as opioids below the reimbursement threshold or sold OTC are not recorded.
They looked as sales data from IMS Health from 2010 to 2014 to represent total opioid utilisation in Australia, including all prescription-only and OTC opioid purchases (those containing low-dose codeine combinations) sold directly to pharmacies and hospitals.
In analyses, opioid use was presented in oral morphine equivalent (OME) kilograms, with the authors suggesting this calculation is more accurate at quantifying true utilisation than defined daily doses (DDDs).
Researchers found PBS/RPBS claims data did not account for 12.4% of prescription-only opioid utilisation in 2014 and 19.1% in 2010, and 18.4% to 25.4% of total opioid use when accounting for OTC preparations.
Oxycodone accounted for almost one third of total opioid use across all study years, while at least 21% of hydromorphone and a further 21% of prescription codeine utilisation were not accounted for in PBS/RPBS claims.
They also found that while OTC codeine items accounted for 40-50% of codeine sales in Australia, they comprised approximately only 6% of total opioid utilisation in OME.
“Hence, at a population level, most of the opioid utilisation across Australia can be accounted for by data on utilisation of prescription opioids,” say the authors.
“Despite increased capture of less expensive (under co-payment) opioid items since 2012, PBS/RPBS claims still underestimate opioid use in Australia, with varying degrees across opioids.”
They add that given claims data primarily records dispensing of subsidised or insured prescription medicines, there is a significant gap in the data from private community prescriptions (potentially accounting for a further 6% of opioid use in total) as well as opioid use by inpatients in public hospitals.
The authors also point out that dispensed quantities or number of packs sold do not directly equate to actual use.
“Further, the impact of the decision to restrict the availability of OTC codeine preparations in Australia from 2018 is yet to be seen.”