title: Using quantile regression to assess disparities in medication adherence.
abstract: OBJECTIVE
  To examine racial/ethnic disparities in medication adherence between Asian and Pacific Islander Americans and Whites.
  
  
  METHODS
  This retrospective data analysis included diabetes patients enrolled in a health plan in Hawaii (N = 43,445). For anti-diabetic, lipid-lowering, and anti-hypertensive medications, quantile regression was estimated at 25(th), 50(th), and 75(th) quantiles to examine the association with race and ethnicity, controlling for other patient characteristics.
  
  
  RESULTS
  Consistently, Filipinos, Native Hawaiians, and other Pacific Islanders were significantly less adherent than Whites. The greatest disparities were found for other Pacific Islanders using lipid-lowering medications, with adjusted differences in medication adherence, with reductions relative to Whites of as much as 19% for lipid-lowering medications for the 25(th) quantile of adherence.
  
  
  CONCLUSIONS
  Whereas the large sample size undoubtedly contributed to the statistical significance, the large magnitude of the disparities, particularly for Filipinos, Native Hawaiians, and other Pacific Islanders, which suggests that these are meaningful differences that need to be addressed. The largest disparities were found at the lowest quantile suggests that they may be occurring among the most vulnerable populations with potentially poor access to care.
authors.affiliation: College of Pharmacy, University of Hawaii, Hilo, HI, USA. dtjuarez@hawaii.edu.
authors.forename: Deborah T
authors.initials: DT
authors.lastname: Juarez
authors.forename: Candace
authors.initials: C
authors.lastname: Tan
authors.forename: James W
authors.initials: JW
authors.lastname: Davis
authors.forename: Marjorie M
authors.initials: MM
authors.lastname: Mau
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000924:Anticholesteremic Agents / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001213:Asian; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000208:ethnology; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D055118:Medication Adherence / Q000208:ethnology*; D008875:Middle Aged; D044468:Native Hawaiian or Pacific Islander; D012189:Retrospective Studies; D044465:White People
chemical_list: D000924:Anticholesteremic Agents; D000959:Antihypertensive Agents; D007004:Hypoglycemic Agents
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