Table 1.

Medicare Part D Gross Spending and Estimated Discounts for Selected Therapeutic Classes, 2016

Therapeutic class	Medicare Part D spending	Average discount	Base-case analysis (n = 80)		Sensitivity analyses excluding drugs with missing discount information (n = 60)		Sensitivity analyses reducing discount by 25% (n = 80)
			Estimated Part D discounts	Proportion of total Medicare Part D discounts	Estimated Part D discounts	Proportion of total Medicare Part D discounts	Estimated Part D discounts	Proportion of total Medicare Part D discounts
Insulins	$12.3Bn	60%	$7.1Bn	24%	$7.1Bn	24%	$5.3Bn	18%
Inhalers	$9.0Bn	59%	$5.3Bn	18%	$3.6Bn	12%	$4.0Bn	14%
Non-Insulin antidiabetics	$6.6Bn	55%	$3.5Bn	12%	$3.5Bn	12%	$2.6Bn	9%
Hepatitis C direct-acting antivirals	$6.4Bn	60%	$3.5Bn	12%	$3.1Bn	11%	$2.3Bn	8%
Direct-acting oral anticoagulants	$5.0Bn	36%	$1.6Bn	6%	$1.4Bn	5%	$1.2Bn	4%
TNF Inhibitors	$4.1Bn	24%	$1.0Bn	3%	$1.0Bn	3%	$0.7Bn	2%
Total	$43.0Bn		$22.0Bn	76%	$19.7Bn	68%	$16.2Bn	55%

As described in the “METHODS” section, gross spending was extracted from the Medicare Part D spending dashboard.⁶ Average discount data was obtained from SSR Health and includes not only rebates from manufacturers to payers but also any other manufacturer concession. Estimated Part D discounts were calculated as the product between gross spending and the average discount. The proportion of total Medicare discounts was estimated as the quotient between the estimated discount for a given class and $29 billion (total manufacturer discounts in Medicare Part D in 2016).³ In sensitivity analyses, we reduced estimates of discounts by 25% (relative difference). For instance, if the estimated discount for a drug in SSR Health data was 66%, we performed sensitivity analyses using 49.5% (75% of 66%) as the estimate