Exhibit 4:

Shares of average annual spending in the catastrophic coverage benefit phase and average 30-day price in 2015 and price change from 2007, by drug class and enrollment in the Low-Income Subsidy (LIS) program

	Share of 2015 spending in catastrophic coverage		Average 2015 30-day price	Average annual price change, 2007– 15
Drug class	Non-LIS	LIS
Higher share of non-LIS than LIS catastrophic spending
Cancer	30%	7%	$5,154	20%
Multiple sclerosis	9	6	5,698	16
Rheumatoid arthritis	5	4	3,870	11
Pulmonary hypertension	4	2	5,099	7
Total or weighted average	48	19	5,018	16
Higher share of LIS than non-LIS catastrophic spending
Mental healtha	2	12	178	−1
Diabetes	7	10	327	16
HIV/AIDS	4	8	1,184	8
Pain	2	3	180	1
Total or weighted average	14	33	278	5
High share of both non-LIS and LIS catastrophic spending
Hepatitis C	14	16	27,620	47

SOURCE Authors’ analysis of data for 2007–15 from the Centers for Medicare and Medicaid Services’ master beneficiary summary files and prescription drug event files for a 100 percent sample of Medicare beneficiaries. NOTES The sample, LIS beneficiaries, and catastrophic coverage status are explained in the notes to exhibit 1. Prices are reported in nominal amounts and represent list prices—that is, before any rebates. Weighted average 30-day prices were computed by dividing total spending that occurred in the catastrophic coverage phase across all beneficiaries (by LIS status) across each of the top four classes, divided by total days supplied in that phase across those top four classes, and multiplying by thirty; essentially weighting the average price of each class by its days supplied. Price increases over time could be due to multiple factors, such as the introduction of new, higher-price products in the drug class; increasing prices of existing products; substitution of higher-price products for lower-price products in the class; or some combination of the three.

^aIncludes antidepressants, antipsychotics, and anticonvulsants.