title: Economic impact of adverse drug events--a retrospective population-based cohort study of 4970 adults.
abstract: BACKGROUND
  The aim was to estimate the direct costs caused by ADEs, including costs for dispensed drugs, primary care, other outpatient care, and inpatient care, and to relate the direct costs caused by ADEs to the societal COI (direct and indirect costs), for patients with ADEs and for the entire study population.
  
  
  METHODS
  We conducted a population-based observational retrospective cohort study of ADEs identified from medical records. From a random sample of 5025 adults in a Swedish county council, 4970 were included in the analyses. During a three-month study period in 2008, direct and indirect costs were estimated from resource use identified in the medical records and from register data on costs for resource use.
  
  
  RESULTS
  Among 596 patients with ADEs, the average direct costs per patient caused by ADEs were USD 444.9 [95% CI: 264.4 to 625.3], corresponding to USD 21 million per 100 000 adult inhabitants per year. Inpatient care accounted for 53.9% of all direct costs caused by ADEs. For patients with ADEs, the average societal cost of illness was USD 6235.0 [5442.8 to 7027.2], of which direct costs were USD 2830.1 [2260.7 to 3399.4] (45%), and indirect costs USD 3404.9 [2899.3 to 3910.4] (55%). The societal cost of illness was higher for patients with ADEs compared to other patients. ADEs caused 9.5% of all direct healthcare costs in the study population.
  
  
  CONCLUSIONS
  Healthcare costs for patients with ADEs are substantial across different settings; in primary care, other outpatient care and inpatient care. Hence the economic impact of ADEs will be underestimated in studies focusing on inpatient ADEs alone. Moreover, the high proportion of indirect costs in the societal COI for patients with ADEs suggests that the observed costs caused by ADEs would be even higher if including indirect costs. Additional studies are needed to identify interventions to prevent and manage ADEs.
authors.affiliation: Nordic School of Public Health NHV, Gothenburg, Sweden; Section of Social Medicine, Department of Public Health and Community Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Hanna
authors.initials: H
authors.lastname: Gyllensten
authors.affiliation: Nordic School of Public Health NHV, Gothenburg, Sweden; Section of Social Medicine, Department of Public Health and Community Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Katja M
authors.initials: KM
authors.lastname: Hakkarainen
authors.affiliation: Department of Drug Research/Clinical Pharmacology, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Futurum - Academy for Health and Care, Jönköping County Council, Jönköping, Sweden.
authors.forename: Staffan
authors.initials: S
authors.lastname: Hägg
authors.affiliation: Nordic School of Public Health NHV, Gothenburg, Sweden; Medical Products Agency, Uppsala, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Carlsten
authors.affiliation: Akademistatistik - Centre for Applied Biostatistics, Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Max
authors.initials: M
authors.lastname: Petzold
authors.affiliation: Department of Learning, Informatics, Management and Ethics - LIME, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Clas
authors.initials: C
authors.lastname: Rehnberg
authors.affiliation: Department of Drug Research/Clinical Pharmacology, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Department of Clinical Pharmacology, County Council of Östergötland, Linköping, Sweden.
authors.forename: Anna K
authors.initials: AK
authors.lastname: Jönsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003625:Data Collection; D064420:Drug-Related Side Effects and Adverse Reactions / Q000191:economics*; D005260:Female; D017048:Health Care Costs; D006801:Humans; D008297:Male; D008875:Middle Aged; D004364:Pharmaceutical Preparations / Q000191:economics*; D012189:Retrospective Studies; D013548:Sweden; D055815:Young Adult
chemical_list: D004364:Pharmaceutical Preparations