Characteristics and Price Increases Among Sole-Source, Off-Patent Drugs in the United States, 2008 to 2018

Abstract

Importance: Some sole-source, off-patent drugs in the United States have undergone substantial price hikes in recent years. Despite increased attention by lawmakers, there are limited data to guide policy.

Objectives: To describe key attributes of sole-source, off-patent, off-exclusivity drugs; to characterize the prevalence of price increases; and to identify attributes associated with price increases.

Design, setting, and participants: In this cross-sectional study, 300 sole-source, off-patent, off-exclusivity drug products met inclusion criteria and were selected for analysis from January 1, 2008, to December 31, 2018. Attributes were identified from multiple sources, and yearly wholesale acquisition cost prices were determined from First Databank.

Main outcomes and measures: The association of drug attributes with the following 2 price change thresholds was measured after adjusting for inflation: 25% or more price increase in a calendar year (wholesale acquisition cost) and 50% or more price increase in a calendar year. The rate of annual price increase over time was also measured.

Results: Of the 300 drug products and 2242 observations analyzed, the overall inflation-adjusted mean increase in drug prices was 8.8% (95% CI, 7.8%-9.8%) per year. Ninety-five drugs (31.7%) increased by 25% or more during any calendar year, and 66 drugs (22.0%) increased by 50% or more during any calendar year. An initial price of less than $2 per unit (adjusted odds ratio [aOR], 2.36; 95% CI, 1.69-3.29), antineoplastic and immunomodulatory class (aOR, 2.72; 95% CI, 1.31-5.65), dermatologic class (aOR, 2.95; 95% CI, 1.80-4.84), oral route (aOR, 2.01; 95% CI, 1.45-2.79), and US Food and Drug Administration (FDA) approval before 1990 (aOR, 1.52; 95% CI, 1.14-2.03) were attributes of drugs that were more likely to be associated with a 25% or more price increase in a calendar year after adjusting for by initial price. Similarly, an initial price of less than $2 per unit (aOR, 2.68; 95% CI, 1.76-4.09), antineoplastic and immunomodulatory class (aOR, 3.07; 95% CI, 1.54-6.12), oral route of administration (aOR, 1.70; 95% CI, 1.11-2.60), and FDA approval before 1990 (aOR, 2.02; 95% CI, 1.40-2.94) were attributes of drugs that were more likely to be associated with a 50% or more price increase in a calendar year after adjusting for by initial price. Price increases of 25% or more were most common in 2014, and price increases of 50% or more were most common in 2013.

Conclusions and relevance: Price increases among sole-source, off-patent drugs are common, and policy interest in this practice is warranted. These findings should inform state drug pricing legislation.

Figure.. Workflow for Generating the Sample of NDAs, NDCs, and GPIs

FDA indicates US Food and Drug Administration; GPIs, Generic Product Identifiers; NDAs, New Drug Applications; and NDCs, National Drug Codes.