percent of opportunities for administration errors in a pediatric nephrology ward (Fontan et al., 2003); 3.9 errors per 100 charts reviewed for all types of medication in an emergency department (Kozer et al., 2002); and 21.7 acetaminophen dosage errors per 100 patients receiving acetaminophen in an emergency department (Losek, 2004).

Only one study reported on errors involving monitoring of the patient for effects (see Table C-21). Using chart review, this study estimated a rate of 4 errors per 1,000 patients (Kaushal et al., 2001).

The majority of pediatric medication error studies identified by the committee were focused on hospitalized patients. Three studies were focused on the ambulatory care setting and two studies on the emergency department setting. Of the three ambulatory care studies, all examined immunizations (see Table C-22). One study, conducted in the United States, defined invalid vaccine doses as doses given before the minimum recommended age, doses not given within the recommended spacing from the previous dose, doses given unnecessarily (defined as 1 year earlier than the required age), and live virus vaccine given too soon after a previous live virus vaccine. This study estimated 4 invalid doses per 100 immunizations given to children, or 36 percent of children being immunized receiving at