That is the question that a recent study by Tisdale et al. (2021) aim to answer. They first look at the top 250 Medicare Part D drugs in terms 2016 total spending based on the 2016 Medicare Part D Prescriber Public Use File. Drug characteristics were identified from the 2016 FDA Orange Book. The authors identified whether or not a drug had a relevant cost-effectiveness analysis (CEA) study using data from the Tufts Medical Center Cost-Effectiveness Analysis Registry. They also use the Tufts CEA Registry to evaluate the quality of the CEA studies.
Based on this approach, the reach the following conclusions:
- Drug spending is highly concentrated. The top 30 drugs accounted for 33.5% of total Part D spending ($48.9 billion), and the top 250 drugs accounted for 84.1% of overall spending ($122.8 billion)
- Part D spending was highest for endocrinology and cardiology. The disease areas where Medicare spent the most on Part D drugs were endocrinology ($23.3 billion), cardiology ($17.5 billion), and pulmonology ($12.0 billion). You’ll note that oncology is not on the list, in part because many oncology-drugs are clinician administered and thus covered by Medicare Part B (rather than Part D).
- A majority of drugs had a CEA study, but many did not. “Of the 250 drugs for which Medicare Part D spending was the greatest, 135 (54.0%) were included in at least 1 cost-effectiveness study…drugs with any cost-effectiveness evidence represented 67.0% of the total spending among the top 250 drugs”
- The importance of CEA studies is growing over time. As shown in the figure below, the number of drugs with a CEA study is growing over time.