title: Adverse drug reaction-related hospitalizations in persons aged 55 years and over: a population-based study in the Netherlands.
abstract: BACKGROUND
  Elderly individuals appear to be particularly at risk of developing adverse drug reactions (ADRs) because of higher rates of polypharmacy, age-related pharmacokinetic changes, pharmacodynamic variations and substantial co-morbidity levels. Thus, the increasing contribution of elderly individuals to the total population means ADR-related hospitalizations are expected to become more frequent. However, a recent study conducted in the Netherlands found that ADR-related hospitalizations had stabilized during the years 1997-2007. Nonetheless, this study did not take into account the number of medicines used.
  
  
  OBJECTIVE
  Therefore, the objectives of this study were to describe the association between age and sex, and the risk of an adverse drug reaction (ADR)-related hospitalization in persons aged 55 years and over in the Netherlands and to correlate these ADR-related hospitalizations with the number of dispensed medicines over the same period.
  
  
  METHODS
  Data on hospital admissions were obtained from the Dutch nationwide registry of hospital discharges. Data from Statistics Netherlands were used to obtain population demographics. Data on dispensed medicinal products were obtained from the Dutch Foundation for Pharmaceutical Statistics. Analyses were performed by calculating relative risks (RRs).
  
  
  RESULTS
  Those aged ≥75 years were at a more than 4-fold increased risk of being hospitalized in comparison with those aged 55-64 years (RR 4.15; 95% CI 4.12, 4.18). In addition, female sex was associated with an increased risk of an ADR-related hospitalization (RR 1.05; 95% CI 1.03, 1.08) in comparison with males. When taking into account the number of dispensings, elderly ≥75 years of age were at an increased risk of being hospitalized for an ADR due to anticoagulants (RR 2.20; 95% CI 2.12, 2.28), antidiabetic agents (RR 3.53; 95% CI 3.39, 3.66), salicylates (RR 1.70; 95% 1.54, 1.86) and antirheumatics (RR 2.19; 95% CI 2.06, 2.33).
  
  
  CONCLUSIONS
  In our study, we showed that elderly aged ≥75 years were at increased risk of an ADR-related hospitalization. Given that the number of elderly and very old will continue to grow, it is of pivotal importance to further endorse drug safety in this vulnerable patient group.
authors.affiliation: Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA, Rotterdam, the Netherlands.|Drug Safety Unit, Inspectorate of Health Care, The Hague, the Netherlands.
authors.forename: Rikje
authors.initials: R
authors.lastname: Ruiter
authors.affiliation: Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA, Rotterdam, the Netherlands.|Department of Hospital Pharmacy, Erasmus MC, Rotterdam, the Netherlands.|Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: Loes E
authors.initials: LE
authors.lastname: Visser
authors.affiliation: Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA, Rotterdam, the Netherlands.|Drug Safety Unit, Inspectorate of Health Care, The Hague, the Netherlands.
authors.forename: Eline M
authors.initials: EM
authors.lastname: Rodenburg
authors.affiliation: Department of Medical Informatics, Erasmus MC, Rotterdam, the Netherlands.|Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, Messina, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Trifiró
authors.affiliation: Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA, Rotterdam, the Netherlands.|Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: Gijsbertus
authors.initials: G
authors.lastname: Ziere
authors.affiliation: Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA, Rotterdam, the Netherlands. b.stricker@erasmusmc.nl.|Drug Safety Unit, Inspectorate of Health Care, The Hague, the Netherlands. b.stricker@erasmusmc.nl.|Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands. b.stricker@erasmusmc.nl.|Department of Medical Informatics, Erasmus MC, Rotterdam, the Netherlands. b.stricker@erasmusmc.nl.
authors.forename: Bruno H
authors.initials: BH
authors.lastname: Stricker
mesh_terms: D000368:Aged; D000375:Aging; D000925:Anticoagulants / Q000009:adverse effects; D018501:Antirheumatic Agents / Q000009:adverse effects; D016208:Databases, Factual; D011307:Drug Prescriptions; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D005260:Female; D006760:Hospitalization / Q000639:trends; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D055553:Prescription Drugs / Q000009:adverse effects*; D012307:Risk Factors; D012727:Sex Characteristics
chemical_list: D000925:Anticoagulants; D018501:Antirheumatic Agents; D007004:Hypoglycemic Agents; D055553:Prescription Drugs