We thank Dr. Rittenhouse for his interest in our paper.
Dr. Rittenhouse is correct that in Table 1 we report the annualized change as the overall percentage increase divided by the number of years since market approval for each DMT and the two CPIs corresponding to the same time periods. This allowed us to show changes in each DMT from introduction onto the market until December 2013 and compare these with the changes in CPI for the corresponding time period. We agree that the labels used for the three columns could lead some readers to misconstrue the data as being the annual growth rate.
We could have presented the data as a cumulative percentage change in price from marketing approval to the present rather than an annualized percentage increase. The ratio of the cumulative increase in DMT prices to CPI increases would remain unchanged from Table 1. For example, there has been a 615% cumulative increase in the price of Avonex relative to an 84% cumulative increase in CPI for prescription drugs since introduction of the DMT until December 2013, a greater than 7-fold difference. For all the MS DMTs, price changes exceed prescription drug inflation during the same period by at least 3-fold.
We appreciate the opportunity to clarify the labeling and method used to generate the data presented in Table 1. We do want to make it clear that this clarification does not alter our analyses or conclusions about the rapid rise in MS DMT costs since 2002.
For disclosures, please contact the editorial office at journal@neurology.org.
Editor's Note: A correction related to the labeling of Table 1 will be published in a future print issue. The Editors thank Dr. Rittenhouse for noting the error.
We thank Dr. Rittenhouse for his interest in our paper.
Dr. Rittenhouse is correct that in Table 1 we report the annualized change as the overall percentage increase divided by the number of years since market approval for each DMT and the two CPIs corresponding to the same time periods. This allowed us to show changes in each DMT from introduction onto the market until December 2013 and compare these with the changes in CPI for the corresponding time period. We agree that the labels used for the three columns could lead some readers to misconstrue the data as being the annual growth rate.
We could have presented the data as a cumulative percentage change in price from marketing approval to the present rather than an annualized percentage increase. The ratio of the cumulative increase in DMT prices to CPI increases would remain unchanged from Table 1. For example, there has been a 615% cumulative increase in the price of Avonex relative to an 84% cumulative increase in CPI for prescription drugs since introduction of the DMT until December 2013, a greater than 7-fold difference. For all the MS DMTs, price changes exceed prescription drug inflation during the same period by at least 3-fold.
We appreciate the opportunity to clarify the labeling and method used to generate the data presented in Table 1. We do want to make it clear that this clarification does not alter our analyses or conclusions about the rapid rise in MS DMT costs since 2002.
For disclosures, please contact the editorial office at journal@neurology.org.
Editor's Note: A correction related to the labeling of Table 1 will be published in a future print issue. The Editors thank Dr. Rittenhouse for noting the error.