Assessment of Medication Errors That Involved Drug Allergies at a University Hospital

T. Aaron Jones, Pharm.D., Jackson A. Como, Pharm.D.


Pharmacotherapy. 2003;23(7) 

In This Article

Abstract and Introduction

Objectives: To determine the reporting accuracy of true patient-related allergies to drugs in a large teaching institution (908 licensed beds), and to identify factors contributing to medication errors that involved drug allergies. Of particular interest was the accuracy of allergy information in the medical record and the occurrence of medication errors that involved penicillin antibiotics.
Methods: From a sample population of 340 patients, 50 adult patients admitted to our university-affiliated hospital who met criteria and had an allergy to selected drugs that was documented in the hospitalwide computer system were randomly selected and interviewed to determine the timing, nature, and extent of the reaction. Furthermore, data were collected from identified Medication Error Reports when an agent was prescribed for a patient with a reported allergy to that agent or class. Prospective data collection was conducted from November 2000-February 2001. Using the information obtained by the patient interview and chart documentation, we assessed the reported allergy. In addition, contributing factors for medication errors that involved drug allergies were identified.
Results: Of the sample population, 133 patients (39%) reported allergies to at least one drug. Allergies to -lactams, sulfonamides, and opioid narcotics were reported in 12.6% (43 patients), 9.1% (31), and 14.4% (49) of the sample population, respectively. Most agents involved in medication errors were -lactam antibiotics, with an overwhelming number of these errors due to piperacillin-tazobactam (51.4%, 36 errors). Other drugs involved were ampicillin (10%, 7 errors), other -lactams (24.3%, 17 errors), opioid narcotics (10%, 7 errors), and sulfonamides (4.3%, 3 errors). Most contributing factors were classified as "MD [prescribing physician] not aware of allergy."
Conclusion: These results suggest a need for ensuring that prescribers review each patient's allergy profile before order entry.

Allergies to drugs can pose a challenge to achieving optimal drug therapy. Reactions that occur because of a drug allergy are responsible for up to 10-15% of the observed reactions in the inpatient setting.[1,2,3,4] Differentiation between true drug allergies and drug intolerance is often not attempted,[1,2,3,4,5] and the term allergic is subsequently ascribed to various adverse drug effects ranging from immunoglobulin E-mediated reactions (i.e., anaphylaxis) to gastrointestinal intolerance. Factors that contribute to poor assessment of an allergy history are numerous and include misinterpretations of the reported allergy and incorrect assessments by improperly trained health care personnel. Patients are prone to self-diagnosis of drug allergies, which often is not investigated and corrected by health care professionals during interviews for their drug history.[1,6,7,8,9,10] Regardless of the reason, improper documentation of drug allergies can cause optimal therapy to be withheld, ultimately resulting in the prescribing of a potentially less effective, more toxic, and even more costly drug.[1,9,10]

Another way that drug allergies can affect patient outcome becomes evident when prescribers and caregivers do not use this information when implementing drug therapy. These potential errors occur when the allergy label is overlooked or when the prescribed drug is not recognized to be a derivative of that class of drugs to which the patient is allergic. An example of this at our institution is the prescribing of a commonly administered broad-spectrum antibiotic piperacillin-tazobactam in patients with documented allergies to penicillins. As similar incidents have occurred in other institutions,[11,12] various policies have been adopted to identify the contributing factors for these types of medication errors. Of note, our computer system (Patient Information Network [PIN]) is based on a physician order entry format, which virtually eliminates transcription errors and allows all drug orders to be reviewed by a pharmacist before being dispensed. However, our computer system currently lacks the programming that would automatically detect and alert prescribers to drug allergies at the time of order entry. Furthermore, free-text descriptions of drug-related allergies are often used in place of the available standard selections.

We sought to determine the accuracy of true patient-related allergies to drugs in our institution and to identify factors contributing to medication errors involving drug allergies. Of particular interest was the accuracy of allergy information in the medical record and the occurrence of medication errors involving penicillin antibiotics.