title: Prevalence and characteristics of adverse drug reactions at admission to hospital: a prospective observational study.
abstract: Adverse drug reactions (ADRs) contribute to poorer patient outcomes and additional burden to the healthcare system. However, data on the true burden, relevant types and drugs causing ADRs are lacking. The aim of this study was to determine the prevalence of ADR-related hospitalization in the general adult population in Singapore and to investigate their characteristics.
  
  
  
  We prospectively recruited 1000 adult patients with unplanned admission to a large tertiary-care hospital. Two independent reviewers evaluated all suspected ADRs for causality, type, severity and avoidability. The prevalence of ADR-related hospitalization was calculated based on 'definite' and 'probable' ADRs. Logistic regression was used to evaluate predictors for having an ADR at admission.
  
  
  
  The prevalence of all ADRs at admission was 12.4% (95% CI: 10.5-14.6%) and ADRs causing admission was 8.1% (95% CI: 6.5-10.0%). The most common ADRs were gastrointestinal-related. The most common drug category causing ADRs were cardiovascular drugs. Patients with ADRs had a longer length of stay than those who did not (median 4 vs. 3 days, P = 1.70 × 10-3). About 30% of ADRs at admission were caused by at least one drug with a clinical annotation in the Pharmacogenomics KnowledgeBase (PharmGKB), suggesting that some of these ADRs may have been predicted by pharmacogenetic testing.
  
  
  
  We have quantified the burden and characteristics of clinically impactful ADRs in the Singaporean general adult population. Our results will provide vital information for efforts in reducing ADRs through targeted vigilance, patient education and pharmacogenomics in Singapore.
authors.affiliation: Translational Laboratory in Genetic Medicine, Agency for Science, Technology and Research, Singapore and the National University of Singapore.
authors.forename: Sze Ling
authors.initials: SL
authors.lastname: Chan
authors.affiliation: Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Ang
authors.affiliation: Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore.
authors.forename: Levana L
authors.initials: LL
authors.lastname: Sani
authors.affiliation: Department of Pharmacy, Singapore General Hospital, Singapore.
authors.forename: Hong Yen
authors.initials: HY
authors.lastname: Ng
authors.affiliation: Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Winther
authors.affiliation: Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore.
authors.forename: Jian Jun
authors.initials: JJ
authors.lastname: Liu
authors.affiliation: Translational Laboratory in Genetic Medicine, Agency for Science, Technology and Research, Singapore and the National University of Singapore.|Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Liam R
authors.initials: LR
authors.lastname: Brunham
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore.|Oncology Pharmacy, National Cancer Centre Singapore, Singapore.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chan
mesh_terms: D000328:Adult; D002317:Cardiovascular Agents / Q000009:adverse effects; D064420:Drug-Related Side Effects and Adverse Reactions / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D005767:Gastrointestinal Diseases / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data*; D015995:Prevalence; D011446:Prospective Studies; D012846:Singapore / Q000453:epidemiology; D062606:Tertiary Care Centers
chemical_list: D002317:Cardiovascular Agents
keywords: adverse drug reactions; hospital admission; pharmacogenomic testing; prevalence