title: Antihypertensive drug prescribing and persistence among new elderly users: implications for persistence improvement interventions.
abstract: BACKGROUND
  The objective of this study was to examine persistence rates and factors influencing persistence for new elderly users of antihypertensive drugs.
  
  
  METHODS
  We conducted a population-based cohort study in Ontario of adults aged 66 years or older to identify new users of antihypertensive medications between 1999 and 2010. Two-year therapy and class persistence were defined as persistence on any antihypertensive medication and persistence only on the same antihypertensive medication class, respectively.
  
  
  RESULTS
  From 1999-2010, the prevalence of antihypertensive drug use increased from 47.8%-60.5% (P < 0.0001). Persistence was evaluated in 420,148 new users of antihypertensive drugs. After 2 years, therapy persistence was 58.9% and varied according to initial class prescribed, from 52.3% for diuretics to 64.1% for angiotensin-converting enzyme inhibitors. Class persistence ranged from 25.3% for diuretics to 35.8% for angiotensin II receptor blockers. Therapy persistence rates were greater in new users from more recent years (adjusted odds ratio [aOR], 1.24; 95% confidence interval [CI], 1.21-1.27). Subgroups that demonstrated poorer persistence included patients older than 75 years (aOR, 0.95; 95% CI, 0.94-0.96), those with lowest neighbourhood income quintile (aOR, 0.81; 95% CI, 0.80-0.83 compared with the highest quintile), those from urban vs rural areas (aOR, 0.83; 95% CI, 0.81-0.84), and those who started on diuretics as initial monotherapy compared with all other drug classes.
  
  
  CONCLUSIONS
  Although 2-year therapy and class persistence were low for new users of antihypertensive drugs, improvements have occurred over the past decade. Our data highlight subgroups to target for future persistence improvement interventions.
authors.affiliation: Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada; Department of Family and Community Medicine, University of Toronto, Toronto, Ontario, Canada; University Health Network-Toronto Western Hospital Family Health Team, Toronto, Ontario, Canada. Electronic address: karen.tu@ices.on.ca.
authors.forename: Karen
authors.initials: K
authors.lastname: Tu
authors.affiliation: Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada.
authors.forename: Laura N
authors.initials: LN
authors.lastname: Anderson
authors.affiliation: Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada; Department of Family and Community Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Debra A
authors.initials: DA
authors.lastname: Butt
authors.affiliation: Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Hude
authors.initials: H
authors.lastname: Quan
authors.affiliation: Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada; Department of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Hemmelgarn
authors.affiliation: Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Norm R
authors.initials: NR
authors.lastname: Campbell
authors.affiliation: Division of General Internal Medicine, University of Alberta, Edmonton, Canada.
authors.forename: Finlay A
authors.initials: FA
authors.lastname: McAlister
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000367:Age Factors; D000368:Aged; D057911:Angiotensin Receptor Antagonists / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D015331:Cohort Studies; D016208:Databases, Factual; D003920:Diabetes Mellitus / Q000453:epidemiology; D004232:Diuretics / Q000627:therapeutic use; D006333:Heart Failure / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D007182:Income; D016015:Logistic Models; D009203:Myocardial Infarction / Q000453:epidemiology; D009864:Ontario / Q000453:epidemiology; D012189:Retrospective Studies; D012424:Rural Population; D049993:Sodium Chloride Symporter Inhibitors / Q000627:therapeutic use; D020521:Stroke / Q000453:epidemiology; D014505:Urban Population; D016903:Drug Monitoring
chemical_list: D000319:Adrenergic beta-Antagonists; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D004232:Diuretics; D049993:Sodium Chloride Symporter Inhibitors