title: Adverse drug events in ambulatory care.
abstract: BACKGROUND
  Adverse events related to drugs occur frequently among inpatients, and many of these events are preventable. However, few data are available on adverse drug events among outpatients. We conducted a study to determine the rates, types, severity, and preventability of such events among outpatients and to identify preventive strategies.
  
  
  METHODS
  We performed a prospective cohort study, including a survey of patients and a chart review, at four adult primary care practices in Boston (two hospital-based and two community-based), involving a total of 1202 outpatients who received at least one prescription during a four-week period. Prescriptions were computerized at two of the practices and handwritten at the other two.
  
  
  RESULTS
  Of the 661 patients who responded to the survey (response rate, 55 percent), 162 had adverse drug events (25 percent; 95 percent confidence interval, 20 to 29 percent), with a total of 181 events (27 per 100 patients). Twenty-four of the events (13 percent) were serious, 51 (28 percent) were ameliorable, and 20 (11 percent) were preventable. Of the 51 ameliorable events, 32 (63 percent) were attributed to the physician's failure to respond to medication-related symptoms and 19 (37 percent) to the patient's failure to inform the physician of the symptoms. The medication classes most frequently involved in adverse drug events were selective serotonin-reuptake inhibitors (10 percent), beta-blockers (9 percent), angiotensin-converting-enzyme inhibitors (8 percent), and nonsteroidal antiinflammatory agents (8 percent). On multivariate analysis, only the number of medications taken was significantly associated with adverse events.
  
  
  CONCLUSIONS
  Adverse events related to drugs are common in primary care, and many are preventable or ameliorable. Monitoring for and acting on symptoms are important. Improving communication between outpatients and providers may help prevent adverse events related to drugs.
authors.affiliation: Division of General Internal Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA. tgandhi@partners.org
authors.forename: Tejal K
authors.initials: TK
authors.lastname: Gandhi
authors.forename: Saul N
authors.initials: SN
authors.lastname: Weingart
authors.forename: Joshua
authors.initials: J
authors.lastname: Borus
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Seger
authors.forename: Josh
authors.initials: J
authors.lastname: Peterson
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Burdick
authors.forename: Diane L
authors.initials: DL
authors.lastname: Seger
authors.forename: Kirstin
authors.initials: K
authors.lastname: Shu
authors.forename: Frank
authors.initials: F
authors.lastname: Federico
authors.forename: Lucian L
authors.initials: LL
authors.lastname: Leape
authors.forename: David W
authors.initials: DW
authors.lastname: Bates
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000706:statistics & numerical data*; D001900:Boston; D003625:Data Collection; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D006801:Humans; D007049:Iatrogenic Disease / Q000517:prevention & control; D008297:Male; D008508:Medication Errors / Q000706:statistics & numerical data*; D008875:Middle Aged; D011320:Primary Health Care; D011446:Prospective Studies