Physician and Patient Adjustment to Reference Pricing for Drugs

Reference pricing has been shown to reduce drug spending in Europe and has been adopted by some employers and labor unions in the United States. Its association with patient cost sharing depends on whether and how quickly physicians adjust their prescribing patterns to favor the least costly alternatives within each therapeutic class. To examine whether the implementation of reference pricing is associated with physicians and patients shifting to lower-cost drugs, thereby reducing consumer cost sharing and the prices paid by employers. This economic evaluation included employees of Catholic organizations who purchased health insurance through the Reta Trust and a random sample of employees of public sector organizations who purchased insurance through the California Public Employees' Retirement System (CalPERS) as a comparison group between July 1, 2010, and December 31, 2017. Data analysis was performed from January 1, 2019, to September 1, 2019. The Reta Trust implemented reference pricing in July 2013; CalPERS did not adopt reference pricing during the study period. Probability that the drug prescribed was the least costly alternative within its therapeutic class, price paid per prescription, and patient cost sharing per prescription. Multivariable, difference-in-differences regression analysis of drug insurance claims was performed for patients before and after implementation of reference pricing, adjusted for patient characteristics, each drug's therapeutic class, and the month and year of the prescription. During the study period, a total of 1.2 million prescriptions were submitted by 34 319 individuals covered by Reta Trust and 2.1 million prescriptions were submitted by 738 159 individuals covered by CalPERS. In the first 2.5 years after implementation of reference pricing, the percentage of prescriptions made for the low-priced drug within each therapeutic class increased by 5.1 percentage points (95% CI, 1.8 to 8.4 percentage points), patient cost sharing increased by 10.3% (95% CI, -1.6% to -23.6%; this difference was not statistically significant), and prices paid decreased by 19.1% (95% CI, -30.2% to -6.2%) for Reta Trust patients compared with CalPERS patients. During the subsequent 2-year postimplementation period, the percentage of prescriptions made for the low-priced drug increased an additional 6.2 percentage points (95% CI, 2.3 to 10.1 percentage points), patient cost sharing decreased by 21.3% (95% CI, -31.2% to -9.9%), and prices paid