T. Joseph Mattingly II, PhD

Credit: Linkedin

Investigators have developed a new method to better create drug price indexes, using hepatitis C virus (HCV) treatments as a case study.¹

A team, led by T. Joseph Mattingly II, PhD, Department of Pharmacotherapy, University of Utah College of Pharmacy, assessed how price index methods can affect estimates of drug price inflation using hepatitis C virus medication as a case study and explored other approaches for constructing a price index.

Drug Price Indexes

It is often difficult to measure drug price inflation because new drugs continually enter the market, while some drugs transition from branded to generic and current inflation indexes do not account for basic market changes. Market price increases are currently measured after new drugs have been launched, which means the public pays higher costs for newer and usually more expensive drugs, but the inflation indexes do not reflect the increase over existing drugs previously used to treat the same condition.

In the cross-sectional study, the investigators used data from outpatient pharmacies to compile a list of all HCV medications that were on the market between 2013-2020. The medications could be brand or generic and the investigators used the National Drug Codes of HCV drugs, a 20% nationally representative sample of Medicare Part D claims from 2013-2020.

Alternative drug price indexes were developed such as product-level vs class-level product and quantity definitions, in which gross vs net price definitions were used. The investigators also created an adjustment and applied it to capture treatment duration because new drugs often require a shorter duration.

Outcomes

The investigators sought main outcomes of the price index value and rate of inflation from 2013-2020 for each methodologic approach to constructing a drug pricing index.

They identified 27 different HCV drug regimens in Medicare Part D claims between 2013-2020 and estimated a 10% gross drug price increase from 2013-2020 for HCV drugs using a product-level approach for measuring inflation.

However, a class-level approach including the higher prices of new drugs resulted in a 31% gross price increase.

After they adjusted for manufacturer rebates to estimate net prices, the investigators fund HCV drug prices decreased by 31% from 2013-2020.

“The findings of this cross-sectional study indicate that the current product-level methods to estimate drug price inflation underestimated price increases for HCV drugs by failing to include the high launch prices of new market entrants,” the authors wrote. “Using a class-level approach, the index captured higher spending on new products at launch. Prescription-level analyses, which did not consider shorter durations of treatment, overestimated price increases.”

HBV Treatment Criteria

A new analysis earlier this year show African Americans are less likely than other races to meet hepatitis B virus (HBV) treatment criteria.²

A team, led by Mandana Khalili, MD, Division of Gastroenterology and Hepatology, University of California, San Francisco, examined whether HBV treatment initiation and outcomes differ among different racial groups.

In the 5727 person-years of follow-up, 504 participants initiated treatment. There was an incident rate of 4.8 per 100 person-years for African American or Black participants, compared to 9.9 per 100 person-years in Asian individuals, 6.6 per 100 person-years in White individuals, and 7.9 per 100 person-years in those of other races (P < .001).

In addition, only 14% of African American or Black participants met the treatment criteria, lower than both Asian (22%) and White (27%) individuals (P = .01).

The cumulative probabilities of treatment initiation after meeting the criteria was not significantly different between the different racial groups. The probability for African American or Black individuals was 0.45 week 48, compared to 0.38 for Asian individuals and 0.40 for White participants. At week 72, the probability was 0.45 for African American or Black individuals, 0.51 for Asian patients, and 0.51 for White participants (P = .68).

In the safety analysis, the incidence of major adverse liver outcomes was 0.1 per 100 person-years. This did not differ by race.

References:

Mattingly TJ, Anderson GF, Levy JF. Comparison of Price Index Methods and Drug Price Inflation Estimates for Hepatitis C Virus Medications. JAMA Health Forum. 2023;4(6):e231317. doi:10.1001/jamahealthforum.2023.1317

Khalili M, Leonard KR, Ghany MG, et al. Racial Disparities in Treatment Initiation and Outcomes of Chronic Hepatitis B Virus Infection in North America. JAMA Netw Open. 2023;6(4):e237018. doi:10.1001/jamanetworkopen.2023.7018