Pharmacoepidemiology of testosterone prescribing in Australia, 1992–2010

Abstract

To describe patterns of testosterone prescribing in Australia over the past two decades by state or territory and by product type. Observational analysis of testosterone prescribing data obtained from two independent data sources--the Pharmaceutical Benefits Scheme (PBS) and IMS, a source of commercial pharmaceutical sales data. Temporal trends in testosterone prescribing--measured as units prescribed (converted into monthly defined doses) and expenditure--to state or territory and product type (injectable, implantable, transdermal and oral). Over two decades, total annual expenditure on testosterone products increased ninefold to $12.7 million according to PBS data and fivefold to $16.3 million according to IMS data. When adjusted for inflation and population growth, expenditure increased 4.5-fold according to PBS data and 2.5-fold according to IMS data. The patterns of testosterone prescribing according to PBS and IMS data were highly congruent. When converted into monthly defined dose units, testosterone prescribing increased over the two decades with approximately twofold differences in total testosterone prescribed per capita between the states and territories with the highest and lowest rates of prescribing. When analysed by product type, the stable market patterns over the first 15 years were disrupted by sharp changes to create market dominance owing to introduction of two new testosterone products--a depot injectable testosterone and a transdermal testosterone gel. The progressive increase in PBS-subsidised testosterone prescribing without changes in proven medical indications or improvements in diagnosis of pathologically based androgen deficiency are likely to be due to promotion-driven non-compliance with PBS prescribing criteria, indicating that more effective implementation of the criteria is needed.