title: Adverse drug events are a major cause of acute medical admission.
abstract: BACKGROUND
  Adverse drug events (ADE) contribute significantly to hospital admissions. Prospective New Zealand data are scant, and the ability of clinical coding to identify ADE associated admissions is uncertain. Outcomes after cessation of causative medications are unknown.
  
  
  OBJECTIVE
  To assess the frequency, nature and causality of ADE associated with acute admissions to General Medicine at Christchurch Hospital.
  
  
  METHODS
  Prospective observational study of patients admitted to our medical team over 20 weeks.
  
  
  RESULTS
  Of 336 admissions, 96 (28.6%) were ADE related. Sixty-five (19.3%) were caused by an ADE, and 31 (9.2%) were contributed to by an ADE. The mean age of non-ADE patients was 64.3 years (range 16-91), which was similar to the mean age of ADE patients (65.9 years; 21-92). However, if intentional overdoses and recreational drug use were excluded, ADE patients were significantly older at 72.4 years (21-92) (P = 0.0007). ADE patients took more regular medications on admission (mean 6.6, range 0-22) than non-ADE patients (mean 5.0, 0-18), (P = 0.003). The average length of stay was similar. The commonest medications implicated were vasodilators, psychotropics and diuretics. The most common adverse effects were postural hypotension and/or vasovagal syncope (29% of ADE), intentional overdoses and recreational drug use (15%) and acute renal failure and/or clinical dehydration (10%). Seventy-six patients had culprit medications stopped or reduced, and this potentially contributed to six readmissions. Coding identified 61% of ADE associated admissions.
  
  
  CONCLUSIONS
  ADE are a common cause of hospital admission. The most frequent problems are postural hypotension and vasovagal syncope, intentional drug misuse and dehydration.
authors.affiliation: Respiratory Department, Christchurch Hospital, Christchurch, New Zealand.
authors.forename: C Y L
authors.initials: CY
authors.lastname: McLachlan
authors.forename: M
authors.initials: M
authors.lastname: Yi
authors.forename: A
authors.initials: A
authors.lastname: Ling
authors.forename: D L
authors.initials: DL
authors.lastname: Jardine
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064420:Drug-Related Side Effects and Adverse Reactions / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy*; D004636:Emergency Service, Hospital / Q000639:trends; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007024:Hypotension, Orthostatic / Q000175:diagnosis / Q000453:epidemiology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D010343:Patient Admission / Q000639:trends; D011446:Prospective Studies; D019462:Syncope, Vasovagal / Q000175:diagnosis / Q000453:epidemiology / Q000628:therapy; D055815:Young Adult
keywords: clinical coding; drug-related side effect and adverse reaction; patient admission; patient readmission; recreational drug