TORONTO — Outpatient medication errors in the treatment of pediatric attention- deficit/hyperactivity disorder are numerous, but few of them seem to result in patient harm, Dr. David Bundy said at the annual meeting of the Pediatric Academic Societies.
An analysis of a national error-reporting database identified 361 outpatient medication errors involving ADHD medications for children aged 3–17 years from 2003 to 2005 in the U.S. Pharmacopeia MEDMARX database, which contains information on more than 1.1 million adverse drug events reported voluntarily by hospitals and health care systems.
Four medications accounted for 98% of all reports: methylphenidate (157 or 43%), dextroamphetamine alone and combined with amphetamine (149 or 41%) bupropion (28 or 8%), and atomoxetine (22 or 6%).
Methylphenidate errors were more likely to involve prescribing errors compared with dextroamphetamine/amphetamine (Adderall; 36% vs. 15%), and less likely to involve dispensing problems (49% vs. 67%).
Because more dextroamphetamine/amphetamine errors occurred during the dispensing phase, those errors were significantly more likely to reach patients than were errors involving methylphenidate (85% vs. 74%), said Dr. Bundy of Johns Hopkins University, Baltimore. Dextroamphetamine/amphetamine errors were three times more likely than were methylphenidate errors to involve the wrong dosage form (22% vs. 8%).
Overall, 297 errors reached patients but did not cause harm, 10 errors reached the patient and required monitoring to confirm no harm and/or intervention to preclude harm, and 2 errors occurred that may have contributed to or resulted in temporary harm and required intervention. There were no deaths related to the errors.
Dr. Bundy suggested that ADHD medications themselves may have properties predisposing them to certain types of errors. He described an ADHD “medication bingo” that includes an array of dosages and formulations, including Adderall XR (5, 10, 15, 20, 25, 30 mg); Adderall (5, 7.5, 10, 12.5, 15, 20, 30 mg); methylphenidate (Concerta) (18, 27, 36, 54 mg); and three formulations of methylphenidate (Ritalin), including Ritalin SR and Ritalin LA.
Although few errors involving ADHD medications appear to be harmful to patients' health, the impact on school performance and behavior may be important, said Dr. Bundy, who disclosed no related conflicts of interest. Moreover, pediatric ADHD outpatient medications are associated with 3.5 million ambulatory visits annually in children under 15 years of age—second only to asthma as a cause of ambulatory care visits for a chronic disease.
Dispensing errors are common, and there are no checks and balances afterward to identify errors, the investigators found. Efforts aimed at reducing ADHD medication errors must include not only physician-based systems, but also dispensing/pharmacy systems, Dr. Bundy said.
Dispensing errors accounted for more than half of the reported errors (218 or 60%), whereas nearly one-quarter (84 or 23%) occurred during prescribing, and more than 1 in 10 (45 or 12%) during administration. The most common type of error was improper dose or quantity (131 or 36%) followed by wrong dosage form (51 or 14%), prescribing error (43 or 12%), omission error (39 or 11%), and wrong patient (32 or 9%).
Limitations of the study included the lack of a denominator, which made an incidence calculation impossible; no verification of report accuracy or completeness; underreporting and reporting bias; a nonrepresentative sample; and a lack of information from patients.
“ADHD-related medication error incidence is significant … so the importance of judicious use of ADHD medications is magnified,” Dr. Bundy said in an interview.
Few errors seem harmful to patients' health, but the impact on behavior and performance at school may be important. DR. BUNDY