One study found that the outpatient use of evidence-based therapies for coronary artery disease is increasing, but remains suboptimal (Newby et al., 2006). The proportion of patients reporting use (consistently or inconsistently) of aspirin, beta-blockers, and lipid-lowering agents increased over time, and in the last year (2002) of the study, the use of aspirin was 83 percent, of beta-blockers 61 percent, and of lipid-lowering agents 63 percent. Rates of consistent use were, however, much lower: for aspirin 71 percent of patients, for beta-blockers 46 percent, and for lipid-lowering agents 43 percent.

Overutilization of medications represents an important problem and is best documented in the treatment of colds, upper respiratory infections, and bronchitis by antibiotics. These infections are common diagnoses in the ambulatory care setting. Such infections are overwhelmingly viral in origin and do not respond to antibiotics (Arroll and Kenealy, 2002; Thomas and Arroll, 2000). Nevertheless, patients are often prescribed antibiotics for these diseases, thereby being exposed to ADEs; increased antibiotic resistance results as well. Although prescribing of unnecessary drugs has not always been considered a medication error (but rather overuse), clearly the problem exists and represents a major opportunity for improvement.

For example, using National Ambulatory Medical Care Survey data for 1992, a study found that 51 percent of adult patients diagnosed as having colds, 52 percent of adult patients diagnosed as having upper respiratory tract infections, and 66 percent of adult patients diagnosed as having bronchitis were treated with antibiotics (Gonzales et al., 1997). A parallel study on antibiotic prescribing for children using the same dataset found similar results: antibiotics were prescribed for 44 percent of patients with colds, 46 percent of patients with upper respiratory tract infections, and 75 percent of patients with bronchitis (Nyquist et al., 1998). A third study, using National Ambulatory Medical Care Survey data for 1996, found that in the emergency department, antibiotics were prescribed for 24 percent of patients with common colds and upper respiratory tract infections and 42 percent of patients with bronchitis (Stone et al., 2000).

Results of later studies indicate that the prescribing of antimicrobials for respiratory tract infections has declined somewhat. Again using National Ambulatory Medical Care Survey data for the period 1989–1990 to 1999–2000 for respiratory tract infections, the prescribing of antimicrobials for children and adolescents decreased from 67 to 38 prescriptions per 100 office visits, and the visit-based prescription rate decreased from 72 to 61 per 100 visits (McCaig et al., 2002). Similarly for adults, the prescribing of antibiotics for acute respiratory infections fell from 60 percent of outpa-