1. Variation in prescribing for type 2 diabetes mellitus in
Ireland in 2013 and 2014
Murphy ME1, Bennett K1, Fahey T1, Smith SM1
1. HRB Centre for Primary Care Research, Royal College of Surgeons, Ireland.
Introduction
Results (continued)
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.
Differences in professional opinion can impact patient decision-making and is one cause for unwarranted variations in care, which is called preference sensitive care {Wallace, 2012 #1}. Preference sensitive variation has been documented in the UK and UK as a cause of medical practice variation {Westert, 2011 #17}.
It is uncertain if geographical variation in the prescribing of newer non- insulin anti-diabetic medications in the Republic of Ireland (RoI) exists.
Causes and effects of variation in standardised precribing
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 .  
Aims
Our aim was to examine the level of variation in the prescribing of anti-diabetic medications, especially newer agents, by geographical areas in Ireland.
Methods
Cross sectional analyses were undertaken on the two main national community drug schemes (the General Medical Services (GMS) and Long Term Illness (LTI) schemes) in the RoI in 2013 and 2014.
Direct standardised rates of individual anti-diabetic medication prescribing per 100,000 population were calculated by local and regional geographical areas. Directly standardised rates per 100,000 population were calculated using the European Standard population and the Central Statistics Office data.
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.
Conclusion
Our results highlight significant geographical variation in the standardised prescribing rates of newer anti-diabetic medications (DPP4-Inhibitors and GLP-1 agonists) in the RoI in cross sectional analyses in 2013 and 2014.
The results cannot tell us if low-prescribing-areas in the RoI are prescribing too little or if high-prescribing-areas are prescribing too much.
We have not identified where the source of the variation in DPP4-inhibitor and GLP- 1 Agonist prescribing comes from. One possible influencer of physician prescribing behaviour are representatives from the pharmaceutical industry, but we cannot infer if variation was effected as a result of their influence.
Variation in the management of T2DM in Ireland has implications on the quality of care delivery and cost.
We believe that the recent launch of integrated national clinical guidelines for T2DM, and a limited chronic disease management contract for T2DM by general practitioners, may have a positive effect on variation and preference-sensitive care {Irish College of General Practitioners, 2016 #19}.
Results
Systematic component of variation
The SCV was over 10 for GLP-1 agonists indicating very high levels of geographical variation.
The SCV was over 5 for DPP4-inhibitors indicating high geographical variation for the newer agents (dropping to 4.05 and 3.77 when the highest and lowest prescribing areas were removed from the analysis).
Table 1: Systematic component of variation and differential of variation of anti-diabetic medication (excluding highest and lowest prescribing areas)
Standardised prescribing rates by geographical area
Prescribing rates of all anti-diabetic medications increased in compared to 2013.
The areas of Waterford and Longford/ West Meath had the highest standardised prescribing rates of all medications.
Males had a higher rate of prescribing, reflecting underlying prevalence of T2DM.
2014
2013
SCV of 17 geogpraphical areas
Differential from lowest to highest prescribing areas
Metformin
1.97
X 1.8
1.73
Sulphonylurea
3.64
X 2.4
2.75
X 2.3
DPP4-I
4.05
X 2.8
3.77
X 3.1
GLP-1 Agonists
10.25
X 4.2
11.36
X 4.3
Acknowledgements
HRB-funded SPHeRE Programme
HRB Centre for Primary Care Research
HSE-Primary Care Reimbursement Services for provision of the data on which the study was based.
References X Y v