is likely that per day, nursing home patients are more likely to experience a medication error than are hospital patients. Monitoring errors are probably the most common type of error in the nursing home setting, but are much more difficult to identify, and no study in this area was found. Because a typical medication pass in long-term care exceeds 2 hours, it is impossible for the nurse to deliver all medications within 1 hour of the scheduled time; thus wrong-time errors are predictably high in this setting. Finally, transitions from the nursing home to other settings are a time of high risk for adverse effects due to prescribing or transcription errors.

For the purposes of this study, the committee examined medication error rates in six different settings within the ambulatory care domain: (1) the interface between care settings, for example, from hospital care to outpatient clinic; (2) the ambulatory clinic; (3) the community pharmacy; (4) the home care setting; (5) self-care; and (6) the school setting. In general, there is little or no understanding of incidence rates in all these areas.

Error rates in ambulatory clinics have been thinly researched (see Table 3-3). One study found that 21 percent of prescriptions in these settings