Changes in drug spending for different age groups during the 1990s? Evidence from Sweden

The objective of this review is to examine how drug spending in different age groups changed during the 1990s. Time series analysis of registered data on prescription drug spending were performed, along with two decompositions, one of which was spending in three components: price, quantity (defined daily dose) and residual. The size of the residual is a measure of the impact of changes in drug treatment patterns on drug spending. The other decomposition was of the quantity component in three subcomponents: defined daily doses per person on medication, population share on medication and population size. Both decompositions are made separately for different age groups. How spending for different age groups has developed in different therapeutic areas was also studied. The main outcome measures were prescription drug spending over time within different anatomical therapeutic chemical groups and across different age groups of the population. It was found that the older the age group, the more drug spending had increased, both in absolute and in relative terms, during the 1990s. However, for some anatomical therapeutic chemical groups, younger age groups have experienced faster spending growth. The most notable example being anatomical therapeutic chemical group N CNS, where spending grew fastest by 350%, for those aged between 20 and 39 years. Furthermore, changed treatment patterns, such as a switch to more expensive drugs, is the main explanation for higher spending in all age groups. Higher spending is also due to a larger number of defined daily doses sold, which is almost totally due to the fact that each person on medication in the year 2000 utilized more defined daily doses than in 1990. Changing age structure explains a negligible share of the increase in drug spending, but elderly patients did have a key role in the spending surge since they increased their per capita spending the most.