Although pharmaceutical claims are an essential data source for pharmacoepidemiological studies, these data potentially under‐estimate opioid utilisation. Therefore, this study aimed to quantify the extent to which pharmaceutical claims from Australia's national medicines subsidy programs (Pharmaceutical Benefits Scheme [PBS] and Repatriation Schedule of Pharmaceutical Benefits [RPBS]) under‐estimate prescription‐only and total national opioid utilisation across time and for different opioids. A secondary aim was to examine the impact of the 2012 policy change to record all PBS/RPBS dispensed medicines, irrespective of government subsidy, on the degree of under‐estimation.
Aggregated data on Australian opioid utilisation were obtained for the 2010 to 2014 calendar years, including all single ingredient and combination opioid analgesic preparations available on prescription or over‐the‐counter (OTC). Total opioid utilisation (oral morphine equivalent kilogrammes) was quantified using sales data from IMS Health and compared with pharmaceutical claims data from the PBS/RPBS.
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. Between 2010 and 2014, 5.6% to 5.3% of buprenorphine, 8.1% to 6.3% fentanyl, 17.7% to 10.7% oxycodone, 18.4% to 11.0% tramadol, 38.4% to 21.0% hydromorphone, and 28.6% to 21.0% of prescription‐only codeine utilisation were not accounted for in PBS/RPBS claims.
Despite increased capture of less expensive (under co‐payment) opioid items since 2012, PBS/RPBS claims still under‐estimate opioid use in Australia, with varying degrees across opioids. The estimates generated in this study allow us to better understand the degree of under‐estimation and account for these in research using Australia's national pharmaceutical claims data.