title: Medication adherence to first-line antihypertensive drug class in a large Chinese population.
abstract: OBJECTIVE
  Suboptimal adherence to antihypertensive agents leads to adverse clinical outcomes. This study aims to evaluate the association between first-line antihypertensive drug class and medication adherence in a large Chinese population.
  
  
  METHODS
  All patients prescribed ≥ one antihypertensive drug in 2001-2003 and 2005 who have paid at least two consecutive clinic visits in the public healthcare system of Hong Kong were included. We excluded patients who have followed-up in the clinics for ≤ 30 days. Interval-based Proportion of Days Covered (PDC) was used to assess medication adherence. All patients were followed-up for up to 5 years. Binary logistic regression analysis was used to evaluate the factors associated with optimal adherence, defined as PDC ≥ 80%.
  
  
  RESULTS
  From 147,914 eligible patients, 69.2% were adherent to the antihypertensive prescriptions. When compared with angiotensin converting enzyme inhibitors (ACEIs), patients initially prescribed α-blockers (adjusted odds ratio [AOR]=0.234, 95% C.I. 0.215-0.256), β-blockers (AOR=0.447, 95% C.I. 0.420, 0.477), thiazide diuretics (AOR=0.431 95% C.I. 0.399, 0.466) and calcium channel blockers (AOR=0.451, 95% C.I. 0.423, 0.481) were significantly less likely to be drug adherers. Angiotensin receptor blockers (ARBs) and fixed-dose combination therapies were similarly likely to be medication adherent. Older age, male gender, visits in general out-patient clinics, residence in urbanized regions, and the presence of comorbidity were positively associated with optimal drug adherence.
  
  
  CONCLUSIONS
  Patients receiving initial prescriptions of ACEIs, ARB and combination therapy had more favorable adherence profiles than the other major antihypertensive classes in real-life clinical practice.
authors.affiliation: School of Public Health and Primary Care, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong.
authors.forename: Martin C S
authors.initials: MC
authors.lastname: Wong
authors.forename: Wilson W S
authors.initials: WW
authors.lastname: Tam
authors.forename: Clement S K
authors.initials: CS
authors.lastname: Cheung
authors.forename: Ellen L H
authors.initials: EL
authors.lastname: Tong
authors.forename: Antonio C H
authors.initials: AC
authors.lastname: Sek
authors.forename: N T
authors.initials: NT
authors.lastname: Cheung
authors.forename: Stephen
authors.initials: S
authors.lastname: Leeder
authors.forename: Sian
authors.initials: S
authors.lastname: Griffiths
mesh_terms: D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D044466:Asian People / Q000208:ethnology*; D016208:Databases, Factual; D005260:Female; D006723:Hong Kong / Q000208:ethnology; D006801:Humans; D008297:Male; D055118:Medication Adherence / Q000208:ethnology*; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods*
chemical_list: D000959:Antihypertensive Agents