To what extent do data from pharmaceutical claims under-estimate opioid analgesic utilisation in Australia?

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.