title: Adverse drug reactions leading to urgent hospital admission in an elderly population: prevalence and main features.
abstract: OBJECTIVE
  To assess the prevalence of urgent hospitalization due to adverse drug reactions (ADRs) in patients aged ≥ 65 years, to compare the in-hospital mortality rates between patients admitted for ADRs and those admitted for other causes, and to describe the ADRs, the used and suspected drugs, and the drug-reaction associations.
  
  
  METHODS
  A cross-sectional study was conducted by using the institutional database of the Pharmacovigilance Programme of Bellvitge University Hospital, a 750-bed tertiary care hospital, with information corresponding to a 7-year period. ADR-related admissions of patients aged ≥ 65 years prospectively identified through a systematic daily review of all admission diagnosis were reviewed.
  
  
  RESULTS
  ADRs were suspected to be the main reason for urgent admission in 1976 out of 60,263 patients aged ≥ 65 years (prevalence of ADR-related hospitalization 3.3 % [95 % CI 3.1-3.4 %]). The crude in-hospital mortality rate was 10.2 % in patients with ADR-related admission and 9 % in patients admitted for other causes (p = 0.077). Most patients (86 %) were exposed to polypharmacy, and a drug-drug interaction was suspected in 49 % of cases. The most frequent drug-reaction associations were acute renal failure related to renin-angiotensin system inhibitors, gastrointestinal bleeding caused by antithrombotics and/or non-steroidal anti-inflammatories, and intracranial bleeding induced by vitamin K antagonists.
  
  
  CONCLUSIONS
  One out of every 30 urgent admissions of patients aged ≥ 65 years is ADR-related. These ADRs can be as serious and life-threatening as any other acute pathology that merits urgent hospital admission. Most cases involve patients exposed to polypharmacy and result from well-known reactions of a few commonly used drugs.
authors.affiliation: Clinical Pharmacology Department, Bellvitge University Hospital, c/ Feixa Llarga s/n, 08907, L'Hospitalet de Llobregat, Barcelona, Spain. cpedros@bellvitgehospital.cat.|Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. cpedros@bellvitgehospital.cat.
authors.forename: Consuelo
authors.initials: C
authors.lastname: Pedrós
authors.affiliation: Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.|Internal Medicine Department, Bellvitge University Hospital, L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Formiga
authors.affiliation: Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.|Internal Medicine Department, Bellvitge University Hospital, L'Hospitalet de Llobregat, Barcelona, Spain.|Albert J. Jovell Institute of Public Health and Patients, Faculty of Medicine and Health Sciences, International University of Catalonia, Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Corbella
authors.affiliation: Clinical Pharmacology Department, Bellvitge University Hospital, c/ Feixa Llarga s/n, 08907, L'Hospitalet de Llobregat, Barcelona, Spain.|Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.|Department of Pathology and Experimental Therapeutics, University of Barcelona, Barcelona, Spain.
authors.forename: Josep Maria
authors.initials: JM
authors.lastname: Arnau
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004347:Drug Interactions; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data*; D006785:Hospitals, University / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D019338:Polypharmacy; D015995:Prevalence; D013030:Spain / Q000453:epidemiology
keywords: Adverse drug reactions; Elderly; Hospitalization; Pharmacovigilance