Assessing the Accuracy of Computerized Medication Histories

Published Online: November 01, 2004
Peter J. Kaboli, MD, MS; Brad J. McClimon, MD, PharmD; Angela B. Hoth, PharmD; and Mitchell J. Barnett, PharmD, MS

Objective: To determine the accuracy of computerized medication histories.

Study Design: Cross-sectional observational study.

Patients and Methods: The study sample included 493 Department of Veterans Affairs primary care patients aged 65 years or older who were receiving at least 5 prescriptions. A semistructured interview confirmed medication, allergy, and adverse drug reaction (ADR) histories. Accuracy of the computerized medication lists was assessed, including omissions (medications not on the computer record) and commissions (medications on the computer record that were no longer being taken). Allergy and ADR records also were assessed.

Results: Patients were taking a mean of 12.4 medications: 65% prescription, 23% over-the-counter products, and 12% vitamins/herbals. There was complete agreement between the computer medication list and what the patient was taking for only 5.3% of patients. There were 3.1 drug omissions per patient, and 25% of the total number of medications taken by patients were omitted from the electronic medical record. There were 1.3 commissions per patient, and the patients were not taking 12.6% of all active medications on the computer profile. In addition, 23.2% of allergies and 63.9% of ADRs were not in the computerized record.

Conclusions: Very few computerized medication histories were accurate. Inaccurate medication information may compromise patient care and limit the utility of medication databases for research and for assessment of the quality of prescribing and disease management.

(Am J Manag Care. 2004;10(part 2):872-877)

Studies have demonstrated that the medication profile in outpatient and inpatient medical charts often is inaccurate.1,2 Due to the lack of reliability of the medical record as an accurate source of medication history, many hospitals and clinics have begun using computerized medication profiles, and many groups and government agencies advocate computerized medical records and physician order entry to reduce the incidence of adverse drug events and medication errors.3-5 However, little is known about the accuracy and reliability of computerized medication lists.

In addition, pharmacy benefit management (PBM) databases are increasingly being utilized in clinical research. Information from these large databases has been used to assess compliance and adverse drug events in several studies.6-8 In addition to these private insurance databases, the Department of Veterans Affairs (VA) has a large pharmacy database used for clinical research. This VA pharmacy database has been utilized to calculate the Chronic Disease Score (RxRisk-V) to assess the burden of chronic disease on treated populations,9 assess healthcare utilization within the VA system,10 and evaluate prescribing practices.11 To our knowledge, no studies have evaluated the validity of clinical data found in computer medical records.

This study was performed to evaluate the agreement between information in the VA computerized medication profile and information obtained through a structured medication history.



The study was conducted at the Iowa City, Iowa VA Medical Center (VAMC) primary care clinics. The Iowa City VAMC is a 100-bed hospital and a primary teaching affiliate of the University of Iowa Carver College of Medicine. Sixty internal medical residents, 10 staff physicians, 4 physician's assistants, and 3 nurse practitioners staff the primary care clinics.


The patients in this evaluation were aged 65 years and older, were enrolled in a primary care clinic at the Iowa City VAMC, and had active prescriptions for 5 or more regularly scheduled nontopical medications. Patients with impaired cognitive function or enrolled in a pharmacist-based anticoagulation clinic were excluded. Patients gave informed consent, and the institutional review board at the University of Iowa Carver College of Medicine and Iowa City VAMC approved the study protocol.


A clinical pharmacist evaluated patients at their clinic visit. The evaluation consisted of a focused record review of the computerized medical record, a semistructured patient interview, identification and classification of medication-related problems, and a history of allergies and adverse drug reactions (ADRs). Medication lists compiled by structured patient interview were compared with computerized medication profiles at the time of the interview to determine overall agreement. Patients were instructed to bring all of their medications with them for the interview.

Accuracy of the computerized medication list was assessed by 3 methods. The first was the percentage of patients who had perfect agreement between the medication profile gathered via structured interview (ie, the actual number and names of the medications taken) and the number and names of the medications on the computerized record. The second method assessed omissions, which were defined as medications that were not on the computer record, but that currently were taken by the patient. To determine the overall percentage of omissions, the denominator was the actual number of medications taken by the patient. Finally, commissions were defined as medications that were on the computer record, but that were not currently taken by the patient. To determine the overall percentage of commissions, the denominator was the total number of medications on the computer record. Omissions and commissions were reported as both the mean number of medications per patient and a percentage of the total number of medications for all patients in aggregate.

The effect of copayment status on commission and omission rates also was examined. Veterans who receive medications dispensed by the VA may be required to make a copayment for their medications. The typical copayment is $7.00 for a 30-day supply of a medication.

Allergy and ADR agreement between computerized profiles and structured patient interview was assessed. An allergy was defined as a known sensitivity or hypersensitivity to a drug, and an ADR was defined as any noxious, unintended, and undesired effect of a drug after doses used in humans for prophylaxis, diagnosis, or therapy. The structured interview was compared with the computerized allergy/ADR information to assess perfect agreement of the allergy/ADR information. Omissions were reported as both the number of patients with an allergy or ADR not included on the medication profile, and the number of allergy and ADR omissions for all patients in aggregate. Commissions included the number of allergies and ADRs found on the computer medical record, but denied by the patient.


Proportions, means, and standard deviations were reported where appropriate. Differences between copayment status were compared with a Student's t test. All analyses were conducted using SAS version 8.1 for Windows (SAS Institute. Cary, NC).


A total of 493 patients were evaluated. Their mean age was 74.3 years, 97.8% were male, and 70.0% made a copayment for their medications (Table 1). Patients had a mean of 10.7 medications on their computer medication profile and were taking a mean of 12.4 medications. Of all medications, 65% were prescription, 23% were over-the-counter (OTC) products, and 12% were vitamins/herbals. The percentage of patients with complete agreement between their computerized medication profile and what they were actually taking was 5.3%.


There was a mean of 1.3 commissions per patient; 12.6% of all medications on the computer list were not being taken by patients (Table 1). There was a mean of 3.1 omissions per patient; 25.0% of all medications the patients were taking were not included on the computerized medication profile. Our results indicate that very few patients had complete agreement between the structured medication history and computerized medication lists.

We also evaluated the effect of copayment status on the accuracy of the medication profile (Table 2). In our sample, 70% of the patients were required to make a copayment for their medications. Patients with a copayment had a mean of 9.6 medications listed on their computerized medication profile, compared with 13.0 in the group without a copayment (P < .01). The copayment group had a mean of 1.3 commissions per patient, and the group without a copayment had a mean of 1.6 commissions per patient (P = .06). That is, in the copayment group, 13.0% of medications were commissions, compared with 12.0% in the group that did not have to make a copayment. Copayment status was not significantly associated with number of commissions.


To evaluate the omissions, the denominator becomes the total number of medications the patient was actually taking. The copayment group was actually taking a mean of 11.8 medications, compared with 13.9 for the group without a copayment (P < .01). The copayment group had 3.4 omissions per patient, and the group without a copayment had 2.4 (P < .01) That is, 28.7% of the medications taken by patients with a copayment were not included on the computerized medication record, compared with only 17.5% for patients who did not have a copayment. Patients with a copayment had a significantly higher number of omissions on their computerized record.

Table 3 lists the commissions and omissions by mutually exclusive drug classes. Cardiovascular (16.2%), topical (13.3%), and gastrointestinal (11.5%) agents represent the drug classes most frequently included on the computerized profile that the patients were no longer taking (commissions). Vitamins/minerals (26%), anticoagulant/antiplatelet agents (12.2%), and gastrointestinal agents (11.5%) were the classes of medications most frequently omitted from the computerized medication list (omissions).


Table 4 lists the top 10 commissions and omissions by individual drug name. Aspirin (5.0%), docusate (3.5%), and albuterol (3.1%) were the 3 agents most likely to be found on the computerized list, but which patients were no longer taking (commissions). Sixty-six percent of all commissions were prescription medications. The individual drugs most frequently omitted on the computerized profile were aspirin (10.4%), multivitamins (8.2%), and acetaminophen (6.7%). Thirty-four percent of all omissions were prescription medications.


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