Are survival benefits keeping up with rising cancer drug costs?

Despite what conventional wisdom says, a paper by Chen et al. (2019) indicates that the answer may be ‘yes’.

The adjusted price per median LYG [life year gained] of a drug increased by $6129 (P = .14) each year from 1995 to 2012,…whereas the adjusted price per mean LYG increased at a markedly slower rate of $476 (P = .88) per year. The positive trend, particularly in the price per median LYG, slowed in recent years. From 2013 to 2017, neither the adjusted price per median LYG ($10 488 reduction per year, P = .44) nor the adjusted price per mean LYG ($412 increase per year, P = .97) increased significantly.

In short, while the point estimate did demonstrate an increase, the results were not statistically different from 0, especially in the case of the mean. Broadly, the authors claim:

…between 1995 and 2012, price increases outstripped median survival gains, a finding consistent with previous literature. Nevertheless, price per mean life-year gained increased at a considerably slower rate, suggesting that new drugs have been more effective in achieving longer-term survival. Between 2013 and 2017, price increases reflected equally large gains in median and mean survival, resulting in a flat profile for benefit-adjusted launch prices in recent years…

How do the authors reach this finding?

The authors use data from Centerwatch to identify all new cancer drugs approved between 1995 and 2017 (excluding drugs treating only cancer-related symptoms or treatment side effects like diarrhea or anemia). This leads to a sample of 181 drug-approved indication pairs.

Median life years gained (LYG) came from clinical trials, whereas mean LYG came from economic analyses in Tufts Cost Effectiveness Analysis (CEA) Registry. The comparator used in the CEA was matched to the comparator used in the trial. To estimate trends in cost per median (or mean) LYG over time, the authors use both fractional polynomial models and linear spline regression models. Note that these regressions control for route of adminstration (i.e., oral vs non-oral). On the one hand, this approach is valid since the cost to produce oral compared to biologic drugs likely varies. On the other hand, cancer patients likely care less about production cost and more about changes in the cost to improve cancer survival over time.

Median vs. mean, which is right?

While many medical researchers focus on gains in median survival, patients actual focus on gains in mean survival. My own research (see Shafrin et al. 2017) shows that patients place a high value on long-term durable gains in survival even if the gains for the typical (i.e., median) patient are not large. Thus, while the median is often easier to obtain from clinical trials for research purposes, patients care more about mean survival gains.


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