title: Adverse drug reaction-related hospitalisations: a population-based cohort study.
abstract: OBJECTIVE
  To evaluate the extent, characteristics and determinants of adverse drug reaction (ADR)-related hospitalisations on a population-based level in 2003.
  
  
  METHODS
  We performed a cohort study in the Integrated Primary Care Information (IPCI) database, a general practitioners (GPs) research database with longitudinal data from electronic patient records of a group of 150 GP throughout the Netherlands. Hospital discharge letters and patient records were reviewed to evaluate ADR-related hospitalisations applying WHO causality criteria. The prevalence of ADR-related hospitalisations per total admissions and the incidence per drug group were calculated. Avoidability and seriousness of the ADRs causing admission were assessed applying the algorithm from Hallas.
  
  
  RESULTS
  We identified 3515 hospital admissions, 1277 elective and 2238 acute. Of the acute admissions, 115 were caused by an ADR giving a prevalence of 5.1% (95% confidence intervals (CI): 4.3-6.1%). The prevalence of ADR-related acute admissions increased with age up to 9.8% (95%CI: 7.5-12.7) for persons >75 years. The ADRs that most frequently caused hospitalisations were gastro-intestinal bleeding with anti-thrombotics, bradycardia/hypotension with cardiovascular drugs and neutropenic fever with cytostatics. The incidence rate of ADR-related hospitalisations per drug group was highest for anti-thrombotics and anti-infectives and was relatively low for cardiovascular drugs. Fatality as a direct consequence of the ADR-related admission was 0.31%. In elderly patients 40% of the ADRs causing hospitalisation were judged to be avoidable.
  
  
  CONCLUSIONS
  The extent and potential avoidability of ADR-related hospitalisations is still substantial, especially in elderly patients. Measures need to be put into place to reduce the burden of ADRs.
authors.affiliation: Pharmaco-Epidemiology Unit, Department of Epidemiology & Biostatistics, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Cornelis S
authors.initials: CS
authors.lastname: van der Hooft
authors.forename: Jeanne P
authors.initials: JP
authors.lastname: Dieleman
authors.forename: Claire
authors.initials: C
authors.lastname: Siemes
authors.forename: Albert-Jan L H J
authors.initials: AJ
authors.lastname: Aarnoudse
authors.forename: Katia M C
authors.initials: KM
authors.lastname: Verhamme
authors.forename: Bruno H C H
authors.initials: BH
authors.lastname: Stricker
authors.forename: Miriam C J M
authors.initials: MC
authors.lastname: Sturkenboom
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D016347:Medical Records Systems, Computerized; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D017891:Pharmacoepidemiology; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence