What drives the prescribing of growth hormone preparations in England? Prices versus patient preferences

OBJECTIVE: The patent expiry of a number of biological medicines and the advent of biosimilars raised the expectations of healthcare commissioners that biosimilars would reduce the high cost of these medicines and produce potential savings to the NHS. We aimed to examine the prescribing pattern of different growth hormone preparations (ready to use and reconstitution requiring) in primary and secondary care in England to determine relative rates of decrease or increase and identify the possible factors influencing prescribing following the introduction of biosimilar growth hormone in 2008. DESIGN: Longitudinal observational study. SETTING AND DATA SOURCES: Primary care prescribing cost and volume data was derived from the NHS business services authority website, and for secondary care from the DEFINE database, between April 2011 and December 2015. OUTCOMES: Quarterly prescribing analysis to examine trends and measure the relationship between usage and price. RESULTS: Expenditure and usage of growth hormone in primary care decreased by 17.91% and 7.29%, respectively, whereas expenditure and usage in secondary care increased by 68.41% and 100%, respectively, between April 2011 and December 2015. The usage of reconstitution requiring products significantly declined in primary care (R²=0.9292) and slightly increased in use in secondary care (R²=0.139). In contrast, the usage of ready-to-use products significantly increased in use in primary (R²=0.7526) and secondary care (R²=0.9633), respectively. Weak or no correlation existed between the usage and price of growth hormone preparations in primary and secondary care. CONCLUSIONS: The price of growth hormone products was not the key factor influencing the prescribing of the biological medicines. The main driver for specific product selection was the ease of use and the number of steps in dose preparation. Prescribers appear to be taking into account patient preferences rather than cost in their prescribing decisions.