title: Frequency and determinants of potential drug-drug interactions in an elderly population receiving regular home visits by GPs--results of the home medication review in the AGnES-studies.
abstract: OBJECTIVE
  There is limited knowledge about prevalence and determinants of potential drug-drug-interactions (pDDI) in the ambulatory health care setting. In this manuscript we analysed the prevalence and determinants of pDDI in the AGnES home visit population (GP-supporting, community-based, e-health-assisted, systemic intervention).
  
  
  METHODS
  779 Home-dwelling patients received an IT-supported home medication review (HMR). The interaction monographs of the ABDA-database were used to identify pDDI. A binary multivariate logistic regression model was used to analyse determinants for occurrence of moderate and serious pDDI, respectively.
  
  
  RESULTS
  Patients (mean age f: 79.8 yrs; m: 76.2 yrs) took a mean number of 6.8 active substances (SD = 3.3) regularly. 626 patients (80.4%) with an HMR had at least one pDDI (mean = 4.8; SD = 4.4). In 454 patients (58.3%) we found at least one pDDI with moderate or serious relevance (mean = 2.9; SD = 2.8). The most frequent moderate pDDI was the combination of potassium excretion diuretics (e.g. hydrochlorothiazide) with anti-inflammatory drugs (e.g. ibuprofen; n = 258 patients). Adjusted for age and gender, multiple binary logistic regression showed significant results for the number of taken active substances (continuous variable; OR = 1.48; 95%-CI 1.382-1.585), metabolic diseases (OR = 1.52; 95%-CI 1.039-2.223), a diagnose of a muscular-skeletal disease (OR = 1.741; 95%-CI 1.204-2.517), infectious disease (OR = 0.127; 95%-CI 0.021-0.783), and gastro-intestinal disease (OR = 0.538; 95%-CI 0.322-0.899).
  
  
  CONCLUSIONS
  Using a comprehensive, computer-assisted HMR in an ambulatory care setting we have identified a high proportion of pDDI of moderate or serious clinical relevance. These pDDI require an intervention from intensified monitoring to a change in medication. Further investigations should focus on clinical outcome of pDDI.
authors.affiliation: Institute for Community Medicine, Dept. Epidemiology of Health Care and Community Health, Ernst Moritz Arndt University of Greifswald, Greifswald, Germany. wolfgang.hoffmann@uni-greifswald.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hoffmann
authors.forename: Neeltje
authors.initials: N
authors.lastname: van den Berg
authors.forename: Jochen René
authors.initials: JR
authors.lastname: Thyrian
authors.forename: Thomas
authors.initials: T
authors.lastname: Fiss
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000706:statistics & numerical data*; D004347:Drug Interactions; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data; D006699:Home Care Services / Q000706:statistics & numerical data*; D006792:House Calls; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D011446:Prospective Studies