title: Changes in Drug Use and Polypharmacy After the Age of 90: A Longitudinal Study of the Danish 1905 Cohort.
abstract: To determine the longitudinal development of drug use in very old adults.
  
  
  
  Longitudinal cohort study with waves in 1998, 2000, 2002, and 2005.
  
  
  
  Nationwide study in Denmark.
  
  
  
  All living Danes born in 1905 were approached in 1998; 2,262 responded at baseline.
  
  
  
  Self-reported use of regularly taken drugs. Mean and median number of drugs and growth curve models were used to identify the change in number of drugs as the cohort aged from 92 to 100.
  
  
  
  The within-person use of drugs increased with age for women (0.19 per year; 95% confidence interval (CI) = 0.15-0.24) and men (0.15 per year; 95% CI = 0.06-0.24). Persons leaving the study prematurely had higher baseline values and a steeper increase in their annual use of drugs. The population-level mean number of drugs increased from baseline (3.6 drugs) to the first follow-up (4.1 drugs) but thereafter remained stable at approximately 4 drugs. Women used more drugs than men at all waves.
  
  
  
  In this first longitudinal study of drug use in nonagenarians, individuals used an increasing number of drugs as they aged. This increase is difficult to detect in cross-sectional analyses of the population-level mean. More efforts to understand what is reasonable prescribing at these older ages are needed.
authors.affiliation: Max-Planck Odense Center on the Biodemography of Aging, University of Southern Denmark, Odense, Denmark.
authors.forename: Jonas W
authors.initials: JW
authors.lastname: Wastesson
authors.affiliation: Max Planck Institute for Demographic Research, Rostock, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Oksuzyan
authors.affiliation: Unit of Epidemiology, Biostatistics and Biodemography, University of Southern Denmark, Odense, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: von Bornemann Hjelmborg
authors.affiliation: Max-Planck Odense Center on the Biodemography of Aging, University of Southern Denmark, Odense, Denmark.|Unit of Epidemiology, Biostatistics and Biodemography, University of Southern Denmark, Odense, Denmark.|Danish Aging Research Center, University of Southern Denmark, Odense, Denmark.|Department of Clinical Biochemistry and Pharmacology and Department of Clinical Genetics, Odense University Hospital, Odense, Denmark.
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
mesh_terms: D000369:Aged, 80 and over; D015331:Cohort Studies; D003718:Denmark; D004358:Drug Therapy / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D019338:Polypharmacy; D057566:Self Report; D012737:Sex Factors
keywords: aged; drug use; longitudinal; nonagenarians; polypharmacy