TABLE 3-10 Rates of Preventable ADEs in Ambulatory Care


Preventable ADE Rate

Proportion of ADEs Preventable (No. of ADEs in study)

ADE Rate

Gurwitz et al., 2003

1.4 per 100 patient-years

28% (1,523)

5 per 100 patient-years

Gandhi et al., 2003

5.4 per 100 patients

20% (181)

27 per 100 patients

  • Preventable ADEs occurring in hospitals—Classen and colleagues (1997) projected 380,000 occurring annually and Bates and colleagues (1995b) 450,000. These are likely underestimates given the higher preventable ADE rate found in another study using more comprehensive ADE identification methods (Jha et al., 1998).

  • Preventable ADEs occurring in long-term care—Gurwitz and colleagues (2005) projected 800,000—again likely an underestimate given the higher ADEs rates of other studies (Gerety et al., 1993; Cooper, 1999).

  • Preventable ADEs among outpatient Medicare patients—Gurwitz and colleagues (2003) projected 530,000.

Underutilization and Overutilization of Medications

Both underutilization of medications (the failure to prescribe medications for which there is an evidence base for reduction in morbidity and mortality) and overutilization of medications (prescribing of medications for which there is no evidence base for reduction in morbidity and mortality) are common in hospitals, nursing homes, and the ambulatory setting. The committee found well-documented evidence of inadequate treatment for acute coronary syndromes, heart failure, chronic coronary disease, atrial fibrillation, bacterial infection prophylaxis, and thrombosis prophylaxis in hospitals. Underutilization of medications in nursing homes and assisted-living facilities relative to national standards is best documented for pain management, congestive heart failure, and use of anticoagulants in stroke prevention and atrial fibrillation, but there is also limited evidence for deficits in use of medications for depression, myocardial infarction prophylaxis, and treatment of osteoporosis. Overutilization of medication is best documented in the treatment of colds, upper respiratory infections, and bronchitis by antibiotics.

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