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Ever since the publication of the Institute of Medicine’s report titled To Err is Human in 1999, increasing attention has been paid to the issue of medical errors in medicine.90 Although most of the research regarding medication errors has focused on adults (Chap. 140), this problem also affects children. Remarks in this section are generally limited to the pediatric literature.
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Approximately 125,000 exposures each year are classified by the AAPCC as therapeutic errors, accounting for approximately 6% of exposures in children younger than 6 years of age, 24% in children 6 to 12 years of age, and 11% in adolescents. For 2007 to 2011, there were a total of 26 deaths attributed to therapeutic errors, representing 3% of all reported deaths in children and adolescents. Eight percent of the AAPCC-reported fatalities in young children were related to therapeutic errors, but only 1% of the adolescent fatalities were related to therapeutic errors. Of children younger than the age of 6 years, approximately 40% of the errors resulting in severe injury or death occur in children younger than the age of 1 year.184
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Medication errors may occur at any phase of a process that includes ordering, order transcription, pharmacy dispensing, preparation and administration of the medication, and monitoring of medication effects. In fact, the same types of errors can occur at different points in the process. Table 32–5 lists the types of errors that can occur, and Table 32–6 provides some examples of errors.
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Most of the analyses of medication errors have occurred in inpatient settings. The reported frequencies of medication errors vary widely—from 0.47% to 5.7% of written orders and from 0.51 to 157 per 1000 patient-days.55,62,77,84,87,151 The variance largely depends on whether the definition of “error” does or does not include prescribing errors, regardless of whether or not they are corrected, and whether potential, or only actual, adverse drug events are included. The reported frequencies also vary depending on whether there is active case finding or whether there is only voluntary reporting.
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In a 2001 study of pediatric inpatients in which orders were actively monitored for a 6-week period, 5.7% of 10,778 prescriptions had errors in the order for the medication, transcription of the order, dispensing or administration of the medication, or monitoring of medication effects (56 per 100 admissions, 157 per 1000 patient-days);871.1% could have potentially caused an adverse effect (10 per 100 admissions, 29 per 1000 patient-days). Eighty-four percent of the errors occurred during the ordering or transcription phase, so most of the errors were intercepted and corrected before drug administration. There were 26 true adverse drug events, but only five were considered preventable errors (0.05%, 0.52 per 100 admissions, 1.8 per 1000 patient-days). Although the overall error rate was similar to that reported by the same group in a study of adults, the rate of errors that could potentially have caused harm was three times greater; 41% of the potentially harmful errors were not intercepted. However, one review suggests that the prescription error rate is higher in adults than in children.101
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Generally, error rates are higher in intensive care units, where the sickest patients are cared for; such patients often receive multiple medications with complex administration regimens.55,77,87,135,151,186,195 Results similar to those from inpatient settings have been reported in pediatric EDs.62,95,153,159,164
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The studies cited suggest that the frequency of significant errors leading to significant adverse drug events is low; however, even a low frequency applied to a large population of patients could result in a large number of patients being harmed. The most important outcome of the analysis would be to try to reduce the overall number of errors to reduce the number of potential and actual adverse drug events.
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The causes of medication errors are numerous, varied, and complex; they are organizational, environmental, and personal, which includes factors such as the level of training, knowledge and competence, the time of day, workload, staff interactions, communications, number of distractions or interruptions, ambient noise, and drug formulation and drug packaging41,57,65,90,189 (Chap. 140).
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Children may be placed at increased risk of a medication error for several reasons: (1) someone other than the child administers the medication, so there is little opportunity to prevent or limit drug administration; (2) a young child cannot warn practitioners about possible problems such as allergies; (3) a young child cannot inform practitioners when he or she is experiencing an adverse event; (4) medication ordering and administration in children frequently requires dose calculations; (5) inexperienced practitioners may be uncomfortable with pediatric dosing or related calculations; and (6) incorrect measurement or dilution of concentrated stock solutions may yield a small volume, which is not perceived as containing a relatively large dose of medication.32,44,65
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One of the most common errors is prescription, preparation, or administration of an incorrect dose, particularly in children, for whom almost every prescription requires knowledge of the patient’s weight and a calculation of a weight-based dose.87,96,100 In addition, even the milligram per kilogram dose may vary depending on the age of the patient or the diagnosis. Although pediatric doses are generally determined on a milligram per kilogram basis, if the weight is recorded in pounds and this weight is used in the calculation, there will be a built-in twofold error. Calculation errors also occur when drug preparation requires dilution of a concentrated stock solution or special compounding.184 Further confusion can arise when mg is written as or misinterpreted as mL or μg in a calculation or vice versa.40
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When an extra zero is added or a required zero is omitted from calculations, written or verbal prescriptions, or in dispensed and administered medications, a 10-fold error occurs. These large errors are common and result in significant under- or overdosing; 10-fold errors have been reported in testing scenarios, case series, and case reports.47,92,93,96,139,147,151,184 These errors are of particular concern because the risk of toxicity generally increases with significant overdose.
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Because the causes of medication error are numerous and complex, the solutions must be multifaceted and interdisciplinary. The approach to the problem is contained within the field of human factors research and potentially requires changes in individual factors such as knowledge; environmental factors such as interruptions; and system problems such as how medications are ordered, stocked, and dispensed90,177,189 (Chap. 140).
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The most commonly recommended solutions to reduce the frequency of medication errors are computerized physician order entry (CPOE) with clinical decision support systems85,185; ward-based clinical pharmacists; and improved communication among and between all levels of medical, nursing, and pharmacy staff.86,99,141,177 In one of the studies cited earlier, it was estimated that these three solutions together could have prevented more than 90% of the potential errors,56 although the effect of interventions other than CPOE has generally not been studied.
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In its simplest form, CPOE eliminates errors related to legibility. Decision support adds the ability to check a prescription against age, weight, dose, allergies, and drug–drug interactions, but it may not prevent ordering the wrong drug or dose, so there is still a need for education and human oversight in additional to other safeguards. The implementation of CPOE is generally associated with at least some reduction in errors related to medication ordering, although an effect on morbidity or mortality has not yet been demonstrated.1,185 Sometimes there are unanticipated consequences associated with computerized systems.91,116,188
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In the future, all inpatient medication orders and outpatient prescriptions may be transmitted electronically, but until that time, it will be necessary to ensure that prescriptions are written legibly and correctly. The Joint Commission and many other groups have issued recommendations to reduce errors in medication ordering (Chap. 140).
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Standardized tests of the math skills necessary to calculate doses and administer medications have demonstrated deficiencies in both nursing and physician groups.17,21,126,130,133,146,152 Tests of this nature may be a means of identifying practitioners at risk for making calculation errors, highlighting areas in need of remediation, and serving as ongoing educational tools.
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As described earlier, there may be an increased risk of medication errors in critical care areas because of severity of illness and intensity of medication therapy. In many cases, such as during resuscitations, critically ill patients require immediate therapy, verbal orders are common, and there is often insufficient time to carefully review all of the particulars related to medication ordering and administration.45,62,96,108,131
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Critical care areas, including the ED, benefit from having precalculated dosing charts available for resuscitation medications and for other commonly prescribed medications; this is a recommendation of the American Heart Association.7 Many clinical units have developed their own dosing schemes. Commercial products, such as the Broselow-Luten system, are also available and have been shown to reduce the number of medication errors in simulated2,107,109,160 and actual resuscitations.150 There has been some controversy related to the ability of these length-based commercial products to accurately predict the weights of children from diverse domestic and international populations for the purpose of medication dose calculation.110,122
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The previous discussion has been almost exclusively related to hospital-based medication use, but significant errors also may occur in outpatient settings.
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Antipyretics are among the most frequently recommended medications for children. Although significant toxicity after unintentional ingestions in toddlers is now rare, administration of multiple supratherapeutic doses of APAP is common and can cause significant hepatotoxicity.94
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In fact, many parents have difficulty calculating the appropriate dose of APAP and measuring out the appropriate amount after it is calculated despite having received instructions and graduated cups or oral-dosing syringes.68,111,119,167,171 Relevant factors related to these errors include the characteristics of the instructions regarding medication measurement and administration, the health literacy of caregivers, and the accuracy of different measuring devices.
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Two of the most commonly used measuring devices are also the most inaccurate—the teaspoon and the graduated cup.153,199 The household teaspoon is not standardized for volume and can easily be confused with a household tablespoon.111 APAP and ibuprofen elixirs are typically packaged with a graduated cup for administration even though graduated syringes are considered the most accurate of the measuring instruments available and are recommended by the AAP for young children. In addition, the instructions and measuring devices distributed with these products, as well as other nonprescription medications, are highly variable and inconsistent.200
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Health literacy and health numeracy are becoming increasingly understood factors with regard to the safe and effective delivery of health care in general and the reduction of the rate of medical errors in particular. Health literacy plays a key role in a caregiver’s ability to read and understand instructions about and labels on prescriptions and nonprescription medications.164 The labels on medication containers are not standardized with respect to the layout and placement of information or the use of abbreviations or units of measure, may be printed in small fonts that are physically difficult to read, and may be difficult to understand by people with lower health literacy or limited English proficiency.106,200,202 Instructions for medication administration have the same problems. Visual cues using pictograms in the instructions or color-coded or premarked syringes are practical ways to improve the accuracy of parental medication dosing.58,198,201