Medication errors common among hospitalised HIV patients

The complexities of antiretroviral medication, especially drug interactions and toxicities, can lead to errors in the way these medications are prescribed and/or taken. A new study published in Clinical Infectious Diseases shows that such errors may be common even in hospital settings, and even when software that should alert prescribers to problems is being used.

Antiretroviral treatment success depends on adherence to correctly prescribed regimens. Drug resistance and excessive toxicity can result from errors including lapses in treatment, or incorrect frequency and/or drug dosage (including the failure to correctly adjust doses to compensate for drug interactions). Several previous studies have shown that medication errors can occur within hospital settings.

In this new study, the research team of Darius Rastegar, Amy Knight and Jim Monolakis reviewed prescribing patterns for HIV-positive inpatients at their own hospital – Johns Hopkins Bayview Medical Center in Baltimore, Maryland. Medication orders at Johns Hopkins are managed using a “computerised provider order entry” (CPOE) system. Drugs and dosages are selected from on-screen lists; a built-in database (updated monthly) issues warnings if it detects interaction conflicts or questionable dosages. Despite this computerised screening system, Rastegar’s team found that errors occurred in a quarter of HIV-positive in-patients admitted over a one year period.

The study group was composed of adult HIV-positive patients, admitted between 1 April 2004 and 31 March 2005, for whom any antiretroviral medication orders were placed. This comprised 160 individuals (average age 43.7 years; 57% male), 32 of whom were admitted more than once, for a total of 209 separate admissions. Prescribing information and lab data for all of these cases were analysed to identify errors. Only uncorrected errors were analysed – any errors corrected before the patient actually received the medication were excluded. A total of 61 uncorrected errors were identified among 54 separate admissions.

What kinds of errors were made?

Errors in medication frequency or dosage were most common – seen in 34 (16.3%) of the admissions. In 18 of these cases, the patient’s kidney function was impaired, but drug dosages were not reduced accordingly. Other errors of this type included administering:

• tenofovir 300 mg twice daily, instead of once daily.
• Kaletra three times daily, instead of twice daily.
• atazanavir 300 mg once daily, without ritonavir boost.

These errors were often, but not always, corrected when the patient was discharged.

Inappropriate (contraindicated) drug combinations were the next most common error, with 12 (5.2%) such occurrences lasting for more than 24 hours. Six patients received proton pump inhibitors (a potent type of stomach antacid) along with atazanavir – an interaction which can significantly lower atazanavir levels. Another six received the cholesterol-lowering drug simvastatin in combination with a protease inhibitor - a combination generally not recommended, since protease inhibitors dangerously boost simvastatin blood levels. Only one of these errors was flagged by the CPOE system.

In eight of the admissions (3.8%), patients received regimens of less than three antiretroviral agents. (Several more patients were already receiving less than three ARVs prior to admission; these were not counted among the errors.) Finally, in seven (3.3%) of the cases, antiretroviral therapy was not administered at all for at least the first 24 hours after admission.

The researchers note that other errors may not have been captured by their study – for instance, errors in medication timing, and failure to meet food restrictions. (Previous studies have shown that these errors are not uncommon.) As stated in the study report: “Ideally, patients receiving HAART who are admitted to the hospital should have a seamless transition… however, our study shows that hospitalisation can place these patients at substantial risk for gaps in effective therapy… More needs to be done … to prevent such errors and to ensure optimal care for hospitalised patients with HIV infection.”