Growth of diabetes drug expenditure decomposed-A nationwide analysis

Abstract

Objectives: The aim of this study was to quantify different factors underlying the growth of diabetes drug expenditure in Finland.

Methods: Data representing purchases of antidiabetic agents between 2003 and 2015 were extracted from a nationwide prescription register. By using Fisher's Ideal Indexes, the per capita expenditure growth for both insulins and non-insulin antidiabetic agents was decomposed into six different determinants: purchase volume, purchase size, switches between therapeutic classes, switches within therapeutic classes, unit costs and switches to generic alternatives.

Results: Between 2003 and 2015, the per capita expenditure on insulins increased by €8.64 and on non-insulins by €13.73. For insulins, holding other factors constant, change in the number of purchases represented a €4.67 increase in expenditure, change in the size of purchases a €4.33 increase and switches between therapeutic classes a €4.07 increase. For non-insulins, change in the number of purchases represented a €10.22 increase in expenditure and switches between therapeutic classes, a €10.17 increase. Changes in purchase size increased the non-insulin per capita expenditure by €1.48. For both insulins and non-insulins, changes in prices and product level switches had decreasing effects on expenditures.

Conclusions: The main drivers of the growth in diabetes drug expenditure were volume growth and switches to newer and more expensive drugs. Price changes, however, had a decreasing effect on the overall diabetes drug expenditure.

Keywords: Diabetes drugs; Drug expenditures; Fisher’s ideal index; Growth.