Background: Antipsychotics and antidepressants are among the fastest-growing therapeutic classes, but the reasons behind recent cost growth are not clear.
Objective: The aim of this study was to assess the explicit factors behind ambulatory antipsychotic and antidepressant cost growth in Finland, as well as the relative importance of the factors associated with the drug group-specific cost growth.
Methods: The data used in this study were retrospectively collected from the Finnish National Health Insurance's register on reimbursed drug purchases. The study period ranged from January 1, 1999, through December 31, 2005, and the obtained data included information on the patient identity number, total cost of the purchase, Anatomic Therapeutic Chemical classification code of the purchased product, and defined daily dose amount of the purchase. Using the retrieved data, antipsychotic and antidepressant cost growth was disaggregated into price and volume factors to create a formula that includes factors about the size of the population, patients per population, volume of treatment per patient, and the mean cost per 1 day of treatment. The relative effect of the factors associated with the drug group-specific cost growth was also examined. Because the purpose of this work was to analyze the factors contributing to the cost growth, we disregarded factors that were negative.
Results: During the study period, the proportion of antipsychotic users of the total population decreased from 2.4% to 2.2% and the mean cost per 1 day of treatment with antipsychotics increased from euro1.37 to euro2.94. The proportion of antidepressant users increased from 4.8% to 6.3%, and mean cost per 1 day of treatment decreased from euro1.06 to euro0.79. In 1999, the consumption of second-generation antipsychotics accounted for 22% of total consumption, and in 2005 their proportion was 62%. Drug choices among anti-depressants did not change substantially. The total cost growth of antipsychotics and antidepressants was 211% and 19%, respectively. Approximately 80% of the antipsychotic cost growth resulted from the rise in the mean cost per 1 day of treatment. The increase in patients per population accounted for approximately 60% of the antidepressant cost growth.
Conclusion: This retrospective analysis found that the factors associated with the growing antipsychotic and antidepressant expenditures in Finland from 1999 through 2005 varied between these 2 drug classes.