OBJECTIVES: To investigate GP prescription rates of IG in England, per product (including biosimilars), and potential associations with key demographic and socio-economic variables.

METHODS: The list of all IG prescriptions by GPs in England between April 2013 and December 2018 was extracted from UK Government databases. Age (mean years) and sex (percentage of females) of patients registered with each GP were retrieved. Socio-economic characteristics (income deprivation [percentage income-deprived], ethnicity [percentage of white people] and rural-urban classification [dichotomous]) of areas where GPs are located were collected. Insulin glargine prescription levels and their temporal trends were analysed. Mixed-effects Poisson regression models were implemented to understand potential associations between prescription rates and key variables. Concentration indices were calculated to evaluate potential inequalities in prescription rates according to income deprivation.

RESULTS: Lantus SoloStar® was the most frequently prescribed IG product, with approximately constant levels since 2013. Toujeo SoloStar Pen® and Abasaglar KwikPen® (biosimilar) prescription levels steeply increased since the first prescribed in 2015. Regression analyses showed the association between IG prescription rates and the variables studied. Income deprivation had a positive effect on prescription levels of Lantus® (SoloStar®/cartridges) and Abasaglar KwikPen®, i.e. the more income-deprived the higher prescription levels were. Additionally, results from regression analyses implied that different prescribing behaviours may exist across Clinical Commissioning Groups (CCGs). Concentration indices did not indicate the existence of substantial inequalities in the distribution of IG prescriptions across the population.

CONCLUSIONS: Results demonstrated that the way GPs in England prescribe IG are associated with the characteristics of the patients they serve. These relationships do not seem to vary greatly across products, including IG biosimilars. Potential variations in prescription levels across CCGs may be related to individual CCG prescribing policies. Understanding the cause of potential variations in prescription levels across GPs and CCGs can help ensure equitable healthcare.