Analyzing reasons for ICU adverse drug events: Look beyond cost and frequency of use
The frequency, severity, and preventability of adverse drug events (ADEs) in intensive care units (ICUs) are not associated with a drug's cost or frequency of use, according to researchers writing in the American Journal of Health System Pharmacy. Researchers from the University of Pittsburgh said critical care pharmacists should set drug monitoring priorities not only by cost alone, but also based on frequency of use and potential for causing an ADE.
Although ADEs occur in some 30% of hospitalized patients, patients in ICUs are at greater risk of having an ADE. University of Pittsburgh assistant professor Sandra Kane-Gill, PharmD, and her colleagues said the increased ADE risk for critically ill patients is related to the higher number of medications administered, acute changes in organ function that affect drug pharmacokinetics, and increased length of hospital stay. For example, the incidence of ADEs in a medical ICU was reported to be 19 events per 1,000 patient days, higher than the 10 events per 1,000 patient days reported for general care units.
In the past, the researchers said, ADE prevention efforts by institutions, professional organizations, and the government has been limited because of the labor and expense involved with ADE surveillance. But the recent public interest in patient safety is shifting the paradigm toward ADE prevention.
The researchers said the presence of pharmacists in ICUs and general medicine units has been shown to reduce the rate of preventable ADEs by 66%. Other techniques that can work include computer-based monitoring of drug interactions, therapeutic duplication, and dosage checks.
Critical care pharmacists have many patient care responsibilities, the researchers said, and thus have a limited amount of time available to perform each function. Budgeting in most hospitals encourages departments to focus on cost reduction rather than cost avoidance when changing processes or improving quality.
Kane-Gill tells Drug Formulary Review there has been a lack of data on ICU adverse events and broader monitoring would be appropriate. She says most facilities don't track ICU-specific data because of a lack of time and resources, but says any specific monitoring increases could help properly allocate drug monitoring priorities.
Monitoring costs not sufficient
"Since ICU drug costs contribute to at least 38.4% of a hospital's total drug costs and have increased at a rate twice that of non-ICUs, many cost-containment efforts encourage pharmacists to monitor the appropriate use of costly ICU medications," the researchers wrote. "However, this strategy may not be the most effective approach, since direct costs are not the only costs associated with drug use. The use of treatment algorithms and guidelines may aid pharmacists in cost-containment efforts but does not address the prevention of ADEs. Further, patients who have an ADE incur an additional cost of $3,000 to $7,000, clearly justifying efforts to increase the prevention and detection of ADEs. Identification of the drugs most commonly associated with ADEs may improve patient safety and contain costs."
Kane-Gill's study sought to compare the rates, preventability, and severity of ADEs associated with: 1) high- and low-cost drugs used in the ICU; 2) high- and low-use drugs in the ICU; and 3) high-cost versus high-use drugs in the ICU.
The researchers defined an adverse drug event as an injury resulting from drug treatment. Preventable ADEs were defined as medication errors in which a patient received a drug resulting in harm. All others were classified as nonpreventable ADEs.
High-cost medications were defined as those accounting for the top 50% of cumulative ICU medication costs for the study period. All remaining medications were considered low-cost. Cost was determined by multiplying units of medication charged to a patient by the pharmacy acquisition cost.
Because of the large number of medications in the pharmacy database and the small number of units associated with many of the drugs, usage was narrowed to those medications most frequently used in an ICU before frequency of use could be quantified. Initial selection of appropriate drugs came from a literature review on ICU drug use. Then, critical care pharmacists practicing in ICUs from 37 different institutions were asked to list the top 10 most frequently used medications in the ICU. High-use medications were defined as the top 50% of all medications used during the study period.
The researchers reported a 32% difference in the number of medications associated with ADEs between the high-cost and high-use groups. Although the difference was not statistically significant, they said, it illustrates that monitoring high-cost and high-use drugs is equally important in the ICU setting.
Three drugs both high-cost and high-use
Only three drugs (lorazepam, mucophenolate, and propofol) were considered both high-cost and high-use, demonstrating a minimal overlap between the categories based on reports generated from an intensive ADE program. Heparin, the medication associated with the most ADEs, was categorized as high-use but low-cost. If medication monitoring had a strictly monetary focus then Heparin would be missed, the researchers said. Although morphine was associated with the second highest number of ADEs, it was not ranked as either a high-use or high-cost drug.
"The large number of ADEs occurring in low-cost and low-use groups and the severity of these ADEs demonstrate that the mechanism to prioritize medication monitoring in the ICU extends beyond cost and use," the researchers said. "Monitoring priorities of critical care pharmacists should include the frequency of ADEs and the potential for incurring injury from a medication."
Although the severity and preventability of ADEs did not vary significantly between high-cost and high-use groups, the high frequency of ADEs indicates opportunity for improvement in ADE prevention, the report said. The most preventable ADEs involved antihypertensives. Anticoagulants were commonly associated with life-threatening events and a prolonged length of stay, further justifying pharmacist monitoring of the use of this class of medications.
Of the 17 high-cost medications, 53% were associated with ADEs. The low-cost group had significantly fewer medications associated with ADEs (9.01%). But the researchers said it should be remembered that 88 low-cost medications were associated with 241 ADEs. And similar percentages of the ADEs were severe and preventable in the high-cost and low-cost groups, although a larger sample size is needed to verify the results.
The researchers said that while it seems logical that high-use medications would be associated with more ADEs because of the frequent exposure, this did not hold true in the study. A similar percentage of medications in the high-use and low-use groups were associated with ADEs (80% vs. 69% respectively). Some 35% of them were severe and 9% were preventable in both groups. High-use medications were not associated with more ADEs than were low-use medications, and this may reflect reduced reliance on ADE reporting or clinicians' familiarity in handling high-use medications.
Monitoring useful
"Monitoring the frequency, preventability, and severity of events using surveillance data is useful for guiding institutional patient safety directives," the researchers said. "For those institutions that do not have an intensive ADE surveillance program, 13 medications (see chart) can be used as a guide for focusing clinicians' monitoring priorities. The results of this study can be used to develop patient safety prevention initiatives for anticoagulants, antibiotics, and sedatives, which could include the implementation of heparin nomograms and sedation protocols."
Download the research report at: www.ajhp.org/cgi/content/full/63/19/1876.
The frequency, severity, and preventability of adverse drug events (ADEs) in intensive care units (ICUs) are not associated with a drug's cost or frequency of use, according to researchers writing in the American Journal of Health System Pharmacy.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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