title: Estimating the incidence of adverse events in Portuguese hospitals: a contribution to improving quality and patient safety.
abstract: BACKGROUND
  Several review studies have shown that 3.4% to 16.6% of patients in acute care hospitals experience one or more adverse events. Adverse events (AEs) in hospitals constitute a significant problem with serious consequences and a challenge for public health. The occurrence of AEs in Portuguese hospitals has not yet been systematically studied. The main purpose of this study is to estimate the incidence, impact and preventability of adverse events in Portuguese hospitals. It is also our aim to examine the feasibility of applying to Portuguese acute hospitals the methodology of detecting AEs through record review, previously used in other countries.
  
  
  METHODS
  This work is based on a retrospective cohort study and was carried out at three acute care hospitals in the Administrative Region of Lisbon. The identification of AEs and their impact was done using a two-stage structured retrospective medical records review based on the use of 18 screening criteria. A random sample of 1,669 medical records (representative of 47,783 hospital admissions) for the year 2009 was analyzed.
  
  
  RESULTS
  The main results found in this study were an incidence rate of 11.1% AEs, of which around 53.2% were considered preventable. The majority of AEs were associated with surgical procedures (27%), drug errors (18.3%) and hospital acquired infections (12.2%). Most AEs (61%) resulted in minimal or no physical impairment or disability, and 10.8% were associated with death. In 58.6% of the AEs' cases, the length of stay was prolonged on average 10.7 days. Additional direct costs amounted to €470,380.00.
  
  
  CONCLUSIONS
  The magnitude of these results was critical, reinforcing the need of more detailed studies in this area. The knowledge of the incidence and nature of AEs that occur in hospitals should be seen as a first step towards the improvement of quality and safety in health care.
authors.affiliation: National School of Public Health, Universidade Nova de Lisboa, Avenida Padre Cruz, 1600-540 Lisboa, Portugal. paulo.sousa@ensp.unl.pt.
authors.forename: Paulo
authors.initials: P
authors.lastname: Sousa
authors.forename: António Sousa
authors.initials: AS
authors.lastname: Uva
authors.forename: Florentino
authors.initials: F
authors.lastname: Serranheira
authors.forename: Carla
authors.initials: C
authors.lastname: Nunes
authors.forename: Ema S
authors.initials: ES
authors.lastname: Leite
mesh_terms: D005260:Female; D006302:Health Services Research; D006761:Hospitals / Q000592:standards*; D006801:Humans; D015994:Incidence; D008297:Male; D019300:Medical Errors / Q000517:prevention & control / Q000706:statistics & numerical data*; D061214:Patient Safety; D011174:Portugal; D058996:Quality Improvement; D012189:Retrospective Studies