title: Impact of a pharmacy benefit change on new use of mail order pharmacy among diabetes patients: the Diabetes Study of Northern California (DISTANCE).
abstract: OBJECTIVE
  To assess the impact of a pharmacy benefit change on mail order pharmacy (MOP) uptake.
  
  
  METHODS
  Race-stratified, random sample of diabetes patients in an integrated health care delivery system.
  
  
  METHODS
  In this natural experiment, we studied the impact of a pharmacy benefit change that conditionally discounted medications if patients used MOP and prepaid two copayments. We compared MOP uptake among those exposed to the benefit change (n = 2,442) and the reference group with no benefit change (n = 8,148), and estimated differential MOP uptake across social strata using a difference-in-differences framework.
  
  
  METHODS
  Ascertained MOP uptake (initiation among previous nonusers).
  
  
  RESULTS
  Thirty percent of patients started using MOP after receiving the benefit change versus 9 percent uptake among the reference group (p < .0001). After adjustment, there was a 26 percentage point greater MOP uptake (benefit change effect). This benefit change effect was significantly smaller among patients with inadequate health literacy (15 percent less), limited English proficiency (14 percent less), and among Latinos and Asians (24 and 16 percent less compared to Caucasians).
  
  
  CONCLUSIONS
  Conditionally discounting medications delivered by MOP effectively stimulated MOP uptake overall, but it unintentionally widened previously existing social gaps in MOP use because it stimulated less MOP uptake in vulnerable populations.
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Karter
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Parker
authors.forename: O Kenrik
authors.initials: OK
authors.lastname: Duru
authors.forename: Dean
authors.initials: D
authors.lastname: Schillinger
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Adler
authors.forename: Howard H
authors.initials: HH
authors.lastname: Moffet
authors.forename: Alyce S
authors.initials: AS
authors.lastname: Adams
authors.forename: James
authors.initials: J
authors.lastname: Chan
authors.forename: Willam H
authors.initials: WH
authors.lastname: Herman
authors.forename: Julie A
authors.initials: JA
authors.lastname: Schmittdiel
mesh_terms: D000368:Aged; D002140:California; D003669:Deductibles and Coinsurance / Q000706:statistics & numerical data; D003920:Diabetes Mellitus / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000191:economics* / Q000627:therapeutic use*; D007356:Insurance, Pharmaceutical Services / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D010593:Pharmaceutical Services / Q000706:statistics & numerical data*; D011177:Postal Service; D012959:Socioeconomic Factors
chemical_list: D007004:Hypoglycemic Agents
keywords: Mail order pharmacy; comparative effectiveness; difference-in-differences; health disparities; inverse probability treatment weighting; marginal structural model; pharmacy benefit designs