Variation in prescribing for type 2 diabetes mellitus in Ireland in 2013 and 2014
Type 2 diabetes mellitus (T2DM) is rising in prevalence, causing a substantial burden to both patients and society. Management of T2DM has seen the arrival of several new classes of medications in recent years, including DPP4-inhibitors and GLP-1 agonists. Variation in the management of T2DM has been postulated as one cause of poor diabetes control. Our aim was to assess variation in the prescribing of anti-diabetic medications, especially newer agents, by geographical region in the Republic of Ireland (RoI).
Cross sectional analyses were undertaken on the two main national community drug schemes in the RoI between 2013 and 2014. Direct standardised rates of individual anti-diabetic medication prescribing per 100,000 population were calculated by local and regional geographical areas. Prescribing was compared across geographical areas using the systematic component of variation (SCV). Estimated total costs of prescribing were calculated per geographical area using the 2013 and 2014 medication wholesale costs.
The SCV was over 10 for GLP-1 agonists indicating very high levels of geographical variation and over 5 for DPP4-inhibitors indicating high geographical variation for the newer agents. Prescribing rates of all anti-diabetic medications increased in 2014 compared to 2013. There were no apparent explanatory factors that affected variation in prescribing, including number and location of specialist services. Geographical variation in the RoI leads to an estimated total cost differential of €600,000 for DPP4-inhibitors and €500,000 for GLP-1 agonists, per 100,000 population, between the highest and lowest prescribing areas.
Substantial geographical variation in the standardised prescribing rate of GLP-1 agonists and DPP4-inhibitors was present in Ireland, in 2013 and 2014. This could represent a variation in the application of guidelines in T2DM management in Ireland and has implications on the quality of care delivery and cost.