A time series analysis of immune checkpoint inhibitor use in the United States Medicare population: 2014–2019

Background: The adoption of immune checkpoint inhibitors (ICIs) has dramatically transformed the treatment of numerous cancers. Medicare is the largest payer in the US and pays for physician-administered drugs through its medical Part B benefit. The aim of this study was to describe trends in ICI utilization and corresponding government expenditures within the US Medicare population. Methods: We analyzed Medicare data to describe trends in total number of claims, total annual expenditures, expenditures per patient, and expenditures per claim for ICIs from January 2014 to December 2019. Results: From 2014 to 2019, utilization rates for each of the seven market approved ICIs in the US increased. Over this time period, total Medicare expenditure on ICIs increased 1916% from $285,506,498 to $5,755,319,571. Concurrently, overall Medicare Part B drug expenditure increased 57% from $23,679,547,748 to $37,271,080,631. Expenditures on ICIs accounted for 40% of the increase in total Medicare Part B drug spending over this time period. Conclusions: The rapid increase in utilization of ICIs has accounted for a disproportionate share of government drug spending growth in the United States. Policymakers can potentially curb spending growth by linking payments to patient outcomes.