title: Duration of initial antihypertensive prescription and medication adherence: a cohort study among 203,259 newly diagnosed hypertensive patients.
abstract: BACKGROUND
  Optimal adherence with antihypertensive medications is crucial to prevent hypertension-related complications. This study evaluated whether the duration of initial antihypertensive prescription is associated with better medication adherence in a large sample of Chinese hypertensive patients.
  
  
  RESULTS
  From a validated clinical database which consists of all patients in the public healthcare sector in Hong Kong, all patients on their first-ever antihypertensive agent from 2001 to 2005 (N=203,259) were included and followed-up for 12 months (and up to 5 years in separate analyses). The average age was 58.7 years (SD 17.3), and the overall rate of optimal adherence (as measured by having the Proportion of Days Covered≥0.80) was 32.4%. The proportion of patients whose initial prescriptions lasted for ≤6 days; 7-14 days; 15-28 days and ≥29 days was 23.7%, 24.3%, 15.1% and 37.0%, respectively. The corresponding proportion of optimal adherence was 18.1%, 20.1%, 31.0% and 50.3%. The binary logistic regression analysis showed that after controlling for age, sex, socioeconomic status, service type, drug class, and district of residence, those whose initial prescription was 7-14 days (adjusted odds ratio [AOR]=1.17, 95% C.I. 1.12-1.22); 15-28 days (AOR=1.90, 95% C.I. 1.82-1.99) and ≥29 days (AOR=4.13, 95% C.I. 3.96-4.31) were significantly more likely to be adherent than those who were prescribed for ≤6 days (all p<0.001). These findings remained significant in separate analyses where the period of follow-up was extended to 5 years.
  
  
  CONCLUSIONS
  Shorter duration of first antihypertensive prescriptions was associated with poorer medication adherence, and this practice should be avoided if possible.
authors: JC School of Public Health and Primary Care, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China.
authors: Martin C S
authors: MC
authors: Wong
authors: JC School of Public Health and Primary Care, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China; Alice Lee Centre for Nursing Studies, National University of Singapore, Singapore.
authors: Wilson W S
authors: WW
authors: Tam
authors: JC School of Public Health and Primary Care, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China.
authors: Harry H X
authors: HH
authors: Wang
authors: Hospital Authority Information Technology Services - Health Informatics Section, Hong Kong, China.
authors: Clement S K
authors: CS
authors: Cheung
authors: Hospital Authority Information Technology Services - Health Informatics Section, Hong Kong, China.
authors: Ellen L H
authors: EL
authors: Tong
authors: Hospital Authority Information Technology Services - Health Informatics Section, Hong Kong, China.
authors: N T
authors: NT
authors: Cheung
authors: Menzies Centre for Health Policy, University of Sydney, Australia.
authors: Stephen R
authors: SR
authors: Leeder
authors: JC School of Public Health and Primary Care, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China. Electronic address: siangriffiths@cuhk.edu.hk.
authors: Sian M
authors: SM
authors: Griffiths
mesh_terms: D000367:Age Factors; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D016017:Odds Ratio; D055553:Prescription Drugs; D016896:Treatment Outcome
chemical_list: D000959:Antihypertensive Agents; D055553:Prescription Drugs
keywords: Chinese population; Cohort study; Duration; Initial antihypertensive prescription; Medication adherence