title: Medication Regimen Complexity and Unplanned Hospital Readmissions in Older People.
abstract: BACKGROUND
  Medication-related problems and adverse drug events are leading causes of preventable hospitalizations. Few previous studies have investigated the possible association between medication regimen complexity and unplanned rehospitalization.
  
  
  OBJECTIVE
  To investigate the association between discharge medication regimen complexity and unplanned rehospitalization over a 12-month period.
  
  
  METHODS
  The prospective study comprised patients aged ≥70 years old consecutively admitted to a Geriatrics Evaluation and Management (GEM) unit between October 2010 and December 2011. Medication regimen complexity at discharge was calculated using the 65-item validated Medication Regimen Complexity Index (MRCI). Cox proportional-hazards regression was used to compute unadjusted and adjusted hazard ratios (HRs) with 95% CIs for factors associated with rehospitalization over a 12-month follow-up period.
  
  
  RESULTS
  Of 163 eligible patients, 99 patients had one or more unplanned hospital readmissions. When adjusting for age, sex, activities of daily living, depression, comorbidity, cognitive status, and discharge destination, MRCI (HR = 1.01; 95% CI = 0.81-1.26), number of discharge medications (HR = 1.01; 95% CI = 0.94-1.08), and polypharmacy (≥9 medications; HR = 1.12; 95% CI = 0.69-1.80) were not associated with rehospitalization. In patients discharged to nonhome settings, there was an association between rehospitalization and the number of discharge medications (HR = 1.12; 95% CI = 1.01-1.25) and polypharmacy (HR = 2.24; 95% CI = 1.02-4.94) but not between rehospitalization and MRCI (HR = 1.32; 95% CI = 0.98-1.78).
  
  
  CONCLUSIONS
  Medication regimen complexity was not associated with unplanned hospital readmission in older people. However, in patients discharged to nonhome settings, the number of discharge medications and polypharmacy predicted rehospitalization. A patient's discharge destination is an important factor in unplanned medication-related readmissions.
authors.affiliation: Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Australia Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia barbara.wimmer@monash.edu.
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Wimmer
authors.affiliation: Discipline of Medicine, University of Adelaide, Adelaide, Australia Discipline of Public Health, University of Adelaide, Adelaide, Australia.
authors.forename: Elsa
authors.initials: E
authors.lastname: Dent
authors.affiliation: Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Australia Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia.
authors.forename: J Simon
authors.initials: JS
authors.lastname: Bell
authors.affiliation: Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Wiese
authors.affiliation: Discipline of Medicine, University of Adelaide, Adelaide, Australia.
authors.forename: Ian
authors.initials: I
authors.lastname: Chapman
authors.affiliation: Discipline of Public Health, University of Adelaide, Adelaide, Australia Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Johnell
authors.affiliation: Discipline of Medicine, University of Adelaide, Adelaide, Australia Aged and Extended Care Services, The Queen Elizabeth Hospital and the Adelaide Geriatrics Training and Research with Aged Care (GTRAC) Centre, University of Adelaide, Adelaide, Australia.
authors.forename: Renuka
authors.initials: R
authors.lastname: Visvanathan
keywords: elderly; hospital readmission; medication regimen complexity