Influence of mandatory generic substitution on pharmaceutical sales patterns: a national study over five years

BACKGROUND: Mandatory generic substitution was introduced in Sweden in October 2002 in order to try to curb escalating pharmaceutical expenditure. The aim of this study was to investigate how sales patterns for substitutable and non-substitutable pharmaceuticals have developed since the introduction of mandatory generic substitution; furthermore, to compare sales patterns in different groups of the population, based on patients' age and gender. METHODS: Five therapeutic groups comprising both substitutable and non-substitutable pharmaceuticals were included. The study period was from January 2000 to June 2005. National sales data were used, covering volumes of dispensed prescription medicines (expressed in defined daily doses per 1000 inhabitants and day) of each pharmacological substance in the therapeutic groups for each age and gender group. Sales patterns for substitutable and non-substitutable pharmaceuticals were compared using a descriptive approach. RESULTS: In most therapeutic groups there has been an increase in the volumes of substitutable pharmaceuticals sold since the introduction of the reform, ranging from one third to three times the initial volume; whereas the volumes of non-substitutable pharmaceuticals have levelled out or declined. There were few gender differences in sales patterns of substitutable and non-substitutable drugs. In three therapeutic groups, sales patterns differed across different age groups, and there was a tendency for volumes of recently introduced non-substitutable pharmaceuticals to be proportionally higher in the youngest age groups. CONCLUSION: Since the introduction of the reform, there has been a proportionally larger increase in sales of substitutable pharmaceuticals compared with sales of non-substitutable pharmaceuticals. This indicates that the reform might have contributed to larger sales of less expensive pharmaceuticals.