title: Antihypertensive medication adherence and mortality according to ethnicity: a cohort study.
abstract: BACKGROUND
  Few studies have evaluated adherence to antihypertensive medication in Chinese and South Asian populations and little is known about the long-term outcome. Our objectives were to compare adherence to antihypertensive medications and assess the association of adherence and long-term mortality in Chinese, South Asian, and white patients with newly diagnosed hypertension.
  
  
  METHODS
  We conducted a retrospective cohort study of patients with hypertension who were new users of antihypertensive medications (1997-2005) using administrative data and a province-wide prescription database from British Columbia, Canada. Antihypertensive medication adherence within 1 year from the date of the first antihypertensive drug prescription was assessed using the 'proportion of days covered' metric. Proportion of days covered ≥ 80% indicated optimal adherence. Patients were followed for up to 10 years for mortality.
  
  
  RESULTS
  There were 16,471 (11.1%) Chinese, 6099 (4.1%) South Asian, and 126,081 (84.8%) white patients who were prescribed antihypertensive medications. Compared with white patients, Chinese (odds ratio, 0.69; 95% confidence interval [CI], 0.67-0.72) and South Asian patients (odds ratio, 0.38; 95% CI, 0.36-0.40) were less likely to be optimally adherent to antihypertensive medications. Optimal adherence was associated with reduced mortality in white patients (risk-adjusted hazard ratio [aHR], 0.89; 95% CI, 0.85-0.93) but not associated with mortality in Chinese (aHR, 0.98; 95% CI, 0.83-1.17) and South Asian patients (aHR, 1.10; 95% CI, 0.84-1.44).
  
  
  CONCLUSIONS
  Chinese and South Asian patients with newly diagnosed hypertension were significantly less likely to adhere to antihypertensive medications than their white counterparts. However, optimal adherence in Chinese and South Asian patients was not associated with mortality.
authors: Department of Epidemiology and Statistic, School of Public Health, Wuhan University, Wuhan, China.
authors: Qing
authors: Q
authors: Liu
authors: Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada. Electronic address: hquan@ucalgary.ca.
authors: Hude
authors: H
authors: Quan
authors: Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.
authors: Guanmin
authors: G
authors: Chen
authors: Center for Health Evaluation and Outcomes Sciences, Vancouver, British Columbia, Canada.
authors: Hong
authors: H
authors: Qian
authors: Division of General Internal Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors: Nadia
authors: N
authors: Khan
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001208:Asia / Q000208:ethnology; D044466:Asian People; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000453:epidemiology; D006429:Hemiplegia / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000208:ethnology / Q000401:mortality*; D007182:Income; D008297:Male; D055118:Medication Adherence / Q000208:ethnology*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology; D010264:Paraplegia / Q000453:epidemiology; D012189:Retrospective Studies; D044465:White People
chemical_list: D000959:Antihypertensive Agents