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Online calculator and chemotherapy order systems reduce medication errors in children

May 08, 2006

Two new studies from the Johns Hopkins Children's Center show that computerizing ordering of chemotherapy and other types of intravenous drug infusions for children greatly reduces the risk of potentially dangerous medical errors.

An online infusion calculator and a computerized drug ordering system, developed under the leadership of Christoph Lehmann, M.D., director of clinical information technology at the Children's Center, have been in use there for about three years, but this is the first time that researchers have measured their impact on medication errors.

Children in general are three times more likely than adults to be victims of medication errors because both ordering and dosing are more complex in children than adults, according to Lehmann. In children, dosing is based on calculations factoring in age, height and weight, and miscalculations and rounding errors could cause life-threatening harm. Dosing errors also cause more ill effects in children because still-developing bodies absorb, metabolize and excrete drugs at different rates than adults and thus have lower tolerance for medication overdose. Children undergoing treatment for cancer are at even greater risk because the general dangers of potent chemicals are compounded by the dosing challenges.

"Our findings reveal that using a Web-based calculator makes it less likely to order and give a child the wrong dose or commit other errors, such as omitting patient information, weight parameters or infusion rates," explains Lehmann, lead author of the Web-based calculator study, which appears in the May 8 issue of Pediatric Critical Care Medicine. "Our calculator stops ordering errors before they can even reach the pharmacy, let alone the patient."

The calculator computes all doses, advises and warns of drug interactions and automatically offers "default" doses and drug dilutions to help doctors avoid overdosing and under-dosing.

For the study, researchers compared handwritten and calculator-generated orders before and after the online calculator was put into use. Twenty-seven percent of handwritten orders were incorrect, with an error rate of 45 errors per every 100 written orders. By contrast, 94 percent of the calculator-generated orders were correct, with an error rate of 6 per 100. The most frequent errors in handwritten orders were wrong dosage and wrong concentration, both of which are considered high-risk errors. None of the calculator-generated orders contained such errors.

To measure the effect of the computerized provider order entry system (CPOE) on pediatric chemotherapy orders, researchers compared 1,259 handwritten orders to 1,116 electronic orders, finding that chemotherapy orders generated with CPOE were less likely to contain dose miscalculations and had fewer omissions of cumulative doses, which is the maximum dose of a medication that can be safely given to a patient over a specific time period. Computerized orders were also less likely to have incomplete nurse safety checklists. Researchers estimate that the computerized system prevented 17 to 18 such errors per every 100 chemotherapy orders.

"Most of these errors may have been caught by pharmacists or nurses before they could have hurt a patient," emphasized Lehmann, "But we wanted to prevent providers from making errors in the first place because some of them may reach the patient."

The chemotherapy order system uses calculators that automatically adjust dosage to the patient's age and weight, thus eliminating the need for complex calculations and reducing the risk of calculation errors. The program reduces the need for handwritten information and free text by forcing providers to make selections from a dropdown menu.

On a cautionary note, researchers found the risk for mismatching medication orders to treatment plans was slightly higher with the use of the electronic chemo order system, probably because current versions do not allow users to match a specific drug order to a recommended one, and because new or experimental drugs do not appear on the system's dropdown menu. This shortcoming will be eliminated after a hospital-wide adoption of a new computer provider order entry system in the near future, researchers say.

"One of the important lessons from this study is that machines alone do not prevent errors, and, in fact, may initially introduce new potential hazards," says co-investigator Robert Arceci, M.D., director of pediatric oncology for The Johns Hopkins Kimmel Cancer Center, where more than 200 children receive cancer treatment each year. "It takes a whole culture of safety and vigilance to prevent errors."

However, the tradeoffs of correct dosing, legible orders and adherence to safety procedures all outweigh the negative effects, researchers say.

Because pediatric chemotherapy is such a complex process, it was crucial for researchers to know exactly where mistakes were most likely to occur before they designed the program. To do so, Lehmann and colleagues used a model called failure modes and effects analysis (FMEA), originally developed by the military. FMEA analysis showed researchers what kinds of errors occurred, where they were most likely to occur and what the potential for harm was. The most frequent errors were misidentification of patients and entering incorrect patient information, such as weight and height. Less frequent were dosage miscalculations and dosing errors due to mismatching drug orders to chemotherapy protocols. Lehmann designed the software application in a manner that precision-targeted these areas.

Based on these findings, researchers recommend the adoption of digitized systems for intravenous drug infusions, as well as chemotherapy orders, in high-risk clinical areas, such as pediatric oncology centers, pediatric intensive care units and emergency rooms.

"What we found extends well beyond pediatric oncology and has potential application in all areas of medicine," says George Kim, M.D., lead author of the chemotherapy study, adjunct faculty in The Johns Hopkins University School of Nursing and faculty in the Division of Health Sciences Informatics. "This system is part of a whole new culture of safety that requires not only change in the system, but also change in the mindset."

Co-investigators in the chemotherapy study included Allen Chen, M.D., professor of pediatric oncology at The Johns Hopkins Kimmel Cancer Center, Sandra Mithcell, R.Ph., of The Johns Hopkins Hospital, and Michelle Kokoszka, R.N., and Denise Daniel, R.N., of the Johns Hopkins Children's Center.

Co-investigators in the online calculator study were George Kim, M.D., instructor of nursing at the Johns Hopkins University School of Medicine; Marlene Miller, M.D., associate professor of pediatrics and director of the Children's Center Quality and Safety Initiative; and Renmeet Gujral, Pharm.D., Michael Veltri, Pharm.D., and John Clark, Pharm.D., of the Department of Pediatric Pharmacy.

Johns Hopkins Medical Institutions