title: Generic substitution does not seem to affect adherence negatively in elderly polypharmacy patients.
abstract: OBJECTIVE
  To investigate the association between generic substitutions and medication adherence in elderly patients with prescribed polypharmacy.
  
  
  METHODS
  Our study included 672 patients aged 65+ years, living at home in the municipality of Aarhus (Denmark), who at the time of enrolment took at least five prescription drugs daily including both short-term and long-term treatment independently of kind of administration route but without assistance. In this paper, only oral drugs for long-term treatment are included in the analysis resulting in median of three drugs per patient. Adherence was assessed by pill counts. Patients with a mean adherence rate <80% across all oral drugs consumed for long-term treatment were categorised as non-adherent. The number of generic substitutions during 1 year was retrieved from the National Health Insurance prescription database. Each change in either a drug's or a manufacturer's name was regarded as a substitution. The association between generic substitution and the mean adherence rate to all drugs was analysed by contingency table analyses and a trend test.
  
  
  RESULTS
  During 1 year, at least one substitution was experienced by 83.6% of patients (n = 562). Patients non-adherent to long-term oral treatment (n = 46) amounted to 8% of all patients who experienced substitutions. Amongst 110 elderly patients (16.4%) who did not experience substitutions, 16% were non-adherent (odds ratio 0.46; 95% confidence interval 0.25-0.82).
  
  
  CONCLUSIONS
  As generic substitution in elderly patients undergoing polypharmacy appears not to affect adherence to long-term drug treatment negatively, there seems to be no obvious reason for avoiding generic substitution in such patients.
authors.affiliation: Department of Geriatrics, Aarhus University Hospital, DK-8000, Aarhus C, Denmark.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Olesen
authors.forename: Philipp
authors.initials: P
authors.lastname: Harbig
authors.forename: Ishay
authors.initials: I
authors.lastname: Barat
authors.forename: Else Marie
authors.initials: EM
authors.lastname: Damsgaard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003718:Denmark; D057915:Drug Substitution / Q000706:statistics & numerical data*; D016568:Drugs, Generic; D006801:Humans; D019338:Polypharmacy; D011446:Prospective Studies; D012307:Risk Factors; D016903:Drug Monitoring
chemical_list: D016568:Drugs, Generic
keywords: adherence; elderly; generic substitution; pharmacoepidemiology; polypharmacy