title: Trends and interaction of polypharmacy and potentially inappropriate prescribing in primary care over 15 years in Ireland: a repeated cross-sectional study.
abstract: OBJECTIVE
  To examine: (1) changes in polypharmacy in 1997, 2002, 2007 and 2012 and; (2) changes in potentially inappropriate prescribing (PIP) prevalence and the relationship between PIP and polypharmacy in individuals aged ≥65 years over this period in Ireland.
  
  
  METHODS
  This repeated cross-sectional study using pharmacy claims data included all individuals eligible for the General Medical Services scheme in the former Eastern Health Board region of Ireland in 1997, 2002, 2007 and 2012 (range 338,025-539,752 individuals). Outcomes evaluated were prevalence of polypharmacy (being prescribed ≥5 regular medicines) and excessive polypharmacy (≥10 regular medicines) in all individuals and PIP prevalence in those aged ≥65 years determined by 30 criteria from the Screening Tool for Older Persons' Prescriptions.
  
  
  RESULTS
  The prevalence of polypharmacy increased from 1997 to 2012, particularly among older individuals (from 17.8% to 60.4% in those aged ≥65 years). The adjusted incident rate ratio for polypharmacy in 2012 compared to 1997 was 4.16 (95% CI 3.23 to 5.36), and for excessive polypharmacy it was 10.53 (8.58 to 12.91). Prevalence of PIP rose from 32.6% in 1997 to 37.3% in 2012. High-dose aspirin and digoxin prescribing decreased over time, but long-term proton pump inhibitors at maximal dose increased substantially (from 0.8% to 23.8%). The odds of having any PIP in 2012 were lower compared to 1997 after controlling for gender and level of polypharmacy, OR 0.39 (95% CI 0.39 to 0.4).
  
  
  CONCLUSIONS
  Accounting for the marked increase in polypharmacy, prescribing quality appears to have improved with a reduction in the odds of having PIP from 1997 to 2012. With growing numbers of people taking multiple regular medicines, strategies to address the related challenges of polypharmacy and PIP are needed.
authors.affiliation: HRB Centre for Primary Care Research, Department of General Practice, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Frank
authors.identifier: http://orcid.org/0000-0001-9838-3625
authors.initials: F
authors.lastname: Moriarty
authors.affiliation: HRB Centre for Primary Care Research, Department of General Practice, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Colin
authors.initials: C
authors.lastname: Hardy
authors.affiliation: HRB Centre for Primary Care Research, Department of General Practice, Royal College of Surgeons in Ireland, Dublin, Ireland Department of Pharmacology & Therapeutics, Trinity Centre for Health Sciences, St James's Hospital, Dublin, Ireland.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Bennett
authors.affiliation: HRB Centre for Primary Care Research, Department of General Practice, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Smith
authors.affiliation: HRB Centre for Primary Care Research, Department of General Practice, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Tom
authors.initials: T
authors.lastname: Fahey
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D057970:Inappropriate Prescribing / Q000191:economics / Q000639:trends*; D007494:Ireland; D008297:Male; D010601:Pharmacology, Clinical / Q000592:standards*; D019338:Polypharmacy; D015995:Prevalence; D011320:Primary Health Care / Q000458:organization & administration*; D012044:Regression Analysis
keywords: CLINICAL PHARMACOLOGY; EPIDEMIOLOGY; PRIMARY CARE