Medication errors in pediatrics

February 2003

Errors in the use of medications occur more commonly than many clinicians may realize. It is not difficult to locate published studies evaluating medication errors, although studies evaluating errors in pediatric patients are not as common. Several guidelines on the prevention of medication errors are available from different professional organizations.

A medication error can be defined as “any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the health care professional, patient or consumer.” (United States Pharmacopoeia, 1995). Medication errors result from flaws in medication-use systems and individual errors.

Numerous types of medication errors have been described (American Society of Health-System Pharmacists, 1993), including: prescribing errors; omission errors (failure to administer an ordered dose to a patient before the next scheduled dose); wrong time error; unauthorized drug error (eg, a dose given to the wrong patient); improper dose error; wrong dosage-form error; wrong drug preparation error; wrong administration-technique error; deteriorated drug error (eg, administration of a drug in which the physical or chemical dosage-form integrity has been compromised); monitoring error; compliance error; Medication errors may be classified as potential errors — an error that is identified prior to medication administration to the patient — or errors of occurrence — an error including medication administration to the patient.

In 1999 the Institute of Medicine published its assessment of the scope of adverse outcomes due to medication errors, estimating that medication errors contribute to the deaths of 44,000 to 98,000 patients each year. From another perspective, the Physicians Insurers Association of America compiled data on over 90,000 malpractice claims in a seven-year period and found that medication errors were the second most frequently cited cause. Pediatrics was ranked sixth out of 16 medical specialties in claim frequency. Although accurate descriptions of medication error incidence rates are difficult to define because of numerous variables, some studies have calculated incidence rates of specific populations. One study of a large teaching hospital recorded a medication error rate of 3.99 per 1,000 medication orders. An evaluation of medication errors at two pediatric hospitals calculated an error rate of 4.5 to 4.9 per 1,000 medication orders. Other studies found medication errors to occur as often as five per 100 medication orders.

Infants and children are at increased risk of medication errors because of several factors: changing physiologic development (affecting drug disposition), the necessity of weight-based dosage individualization, lack of drug dosage forms and concentrations for many products and a lack of pediatric information and FDA-approved labeling for many drugs.

Published studies

Relatively few studies have evaluated medication errors in the pediatric population. Folli prospectively evaluated medication errors at two pediatric teaching hospitals. Medication errors occurred at a rate of 4.5 to 4.9 per 1,000 medication orders. Children younger than 2 years of age and ICU patients were at greatest risk. Not surprisingly, incorrect medication dosing was the most common error identified. Antimicrobial medications were the most common class of drugs to be involved with errors. Although no patient was directly injured by an identified medication error, 5% to 6% of the errors were considered to be potentially lethal.

Kaushal also prospectively studied medication orders in two academic pediatric hospitals and found medication errors to occur at a rate of 5.7%. Potential adverse drug events occurred at a rate of 1.1% — a rate threefold higher than a similar study of hospitalized adults. Neonates were exposed to a higher rate of medication errors. Similar to Folli’s study, incorrect dosing and anti-infective drugs were most commonly involved. Sixteen percent of the potential adverse drug events were potentially life-threatening. The study investigators concluded that computerized physician order entry and ward-based clinical pharmacists could potentially have prevented more than 90% of potential adverse drug events.

Several published studies have evaluated “tenfold medication errors.” Tenfold medication errors, or decimal errors, occur from misplacing or misreading decimal points and have the potential for significant adversity. A recently published study (Lesar, 2002) evaluated tenfold medication errors in a large teaching hospital (19% pediatric beds). Of 200 identified medication errors, 39 (19.5%) occurred in pediatric patients, with antimicrobials being the class of drugs most commonly involved. A misplaced decimal point was the most common error mechanism among the errors involving pediatric patients. Overall, 51.3% of the pediatric medication errors were overdoses and 48.7% were underdoses. In a separate study of the same institution, Lesar evaluated medication errors involving dosage equations. Medication errors of pediatric patients were most commonly identified (69.5%), and again, antibiotics were the most commonly affected drug class. Nearly one-half of these medication errors were assessed as placing the patient at risk for a serious adverse outcome. Most medication errors were due to errors in decimal point placement, mathematical calculation or expression of dosage regimen.

Additional studies have evaluated the ability of physicians to calculate medication doses. Rowe used written tests of basic dosage calculation to evaluate the house staff of a tertiary pediatric hospital on two occasions, separated by two years. Four percent to 8% of calculated doses were in error. More than 10% of the tested residents calculated a tenfold medication error dosing error. In an attempt to correct deficiencies, an education program followed each examination period. Authors of these studies have recommended that new house staff be tested for drug dose calculation deficiencies.

Several professional organizations have published recommendations on medication error prevention (Table 1). Recommendations from the AAP were published in 1998. Other recommendations specific to pediatrics include those of the Pediatric Pharmacy Advocacy Group. The American Society of Health-System Pharmacists has published extensive guidelines and recommendations on medication errors in separate documents — preventing medication errors in hospitals and error prevention in cancer chemotherapy. All of these guidelines offer specific recommendations on how to avoid medication errors and are directed separately to prescribers, pharmacists, nurses, and patients/caregivers.

Table 2 lists several specific recommendations for prevention of medication errors as listed in the above organization guidelines. Readers should view these documents directly when initiating or evaluating medication error prevention policies.

For more information:

• Lesar TS. Errors in the use of medication dosage equations. Arch Pediatr Adolesc Med. 1998;152:340-344.
• Rowe C. Errors by pediatric residents in calculating drug doses. Arch Dis Childr. 1998;79:56-58.
• Lesar TS. Tenfold medication dose prescribing errors. Ann Pharmacother. 2002;36:1833-1839.
• Kaushal R. Medication errors and adverse drug events in pediatric inpatients. JAMA. 2001;285:2114-2120.
• Folli HL. Medication error prevention by clinical pharmacists in two children’s hospitals. Pediatrics. 1987;79:718-22.