Why did drug spending increase during the 1990s? A decomposition based on Swedish data.

Abstract

To decompose drug spending in Sweden between the years 1990 and 2000. This paper updates a previous study, which looked at the period 1990-1995, by providing an additional 5 years of data (1995-2000) and extending the previous analysis in a number of ways. The paper builds on the earlier work that showed that changes in drug spending could be decomposed into three components: price, quantity and a residual. The size of the residual is a measure of the impact of changes in drug treatment patterns on drug spending. The data set used in this paper was collected from Apoteket AB (The National Corporation of Swedish Pharmacies) and was based on comprehensive information (inpatients as well as outpatients) on drug deliveries from wholesalers to pharmacies. Data were obtained for aggregate drug spending (from 1990-2000) and for spending according to anatomical therapeutic chemical (ATC) classification system group. Real drug spending increased by 119% during the study period. The residual rose by 67% indicating the switch from cheaper to more innovative and expensive drug therapies was a major cost driver. Real drug spending would have increased by about 31% if there had been no changes in treatment patterns. The second driver of drug spending was the quantity of drugs consumed, which increased by 41%. The main reason for the larger quantity sold appears to be increases in the intensity of medication in terms of defined daily doses per patient, rather than a larger number of patients starting drug treatment. Real prices decreased during the 10-year study period. We found large differences between ATC groups in terms of spending growth. The ATC groups that have contributed the most to the increase in spending are: drugs that affect the CNS (N), the alimentary tract and metabolism (A) and the cardiovascular system (C), which are also the three largest groups in terms of sales. For all three groups, it was the residual that mainly drove costs. This study indicates very clearly that the main driving force behind the increase in drug costs in Sweden between 1990 and 2000 was the change in drug therapy from old to new and more innovative and expensive drug therapies. This shows the importance of carrying out economic evaluations of new more costly drugs in order to make an assessment of the social benefits of a switch from a cheaper to a more expensive drug.