HealthDay News — Market competition levels are associated with changes in the price of generic drugs, according to a study published in the Annals of Internal Medicine.1
Chintan V Dave, PharmD, from the University of Florida in Gainesville, and colleagues conducted a retrospective study involving prescription claims for commercial health plans from 2008 to 2013. They calculated the Herfindahl-Hirschman Index (HHI) by summing the squares of individual manufacturers’ market shares for each 6-month period, with higher values indicating a less competitive market.
In each period, the authors estimated the average drug prices for generic drugs. The HHI value estimated in the first half of 2008 was modeled as a fixed covariate.
The researchers identified a cohort of 1120 generic drugs from 1.08 billion prescription claims. Price changes of −31.7%, −11.8%, 20.1%, and 47.4% were seen for drugs with quadropoly (HHI value of 2500), duopoly (HHI value of 5000), near-monopoly (HHI value of 8000), and monopoly (HHI value of 10,000) levels of baseline competition, respectively, over the study period.
“Market competition levels were associated with a change in generic drug prices,” the authors write. “Such measurements may be helpful in identifying older prescription drugs at higher risk for price change in the future.”
- Dave CV, Kesselheim AS, Fox ER, Qiu P, Hartzema A. High generic drug prices and market competition: a retrospective cohort study. Ann Intern Med. 2017; 167(3):145-151.