Four percent of hospitalized adolescents and adults at two academic tertiary care medical centers received supratherapeutic doses of acetaminophen during their stays, according to a report published online Nov. 12 in Archives of Internal Medicine.
"These were not isolated events but often were successive and overlapping." Nearly half of the exposed patients received 5 g or more of acetaminophen per day, and 40% received excessive dosing for 3 or more days, said Dr. Li Zhou of Partners HealthCare System, Wellesley, Mass., and her associates.
Such overmedicating puts patients at unnecessary risk for hepatotoxicity, acute liver failure, and even death. In this study, even inpatients at specific risk for liver damage didn’t escape excessive dosing with acetaminophen: 22% of the elderly and 18% of patients with existing chronic liver disease were given acetaminophen in amounts exceeding their recommended limit of 3 g/day, said Dr. Zhou, who is also at Brigham and Women’s Hospital and Harvard Medical School, Boston, and her colleagues.
The risk factors most strongly associated with supratherapeutic dosing were receiving recurring scheduled dosing (that is, standing orders) as opposed to as-needed or one-time-only administration, which carried a hazard ratio of 16.6; receiving multiple products containing acetaminophen, which carried a hazard ratio of 2.4 for each additional product; and receiving products containing 500 mg of acetaminophen, which carried an HR of 1.9.
The investigators used the hospitals’ electronic medication administration record systems to assess acetaminophen exposure in the inpatient setting – a topic that has received little attention from researchers before now, they wrote. The study population comprised the 14,411 inpatients aged 12 and older who received any acetaminophen during their stays in a 3-month period. That accounts for about 61% of the entire patient population hospitalized at the two centers during the study period.
The average age of the study subjects was 55 years (range, 12-110 years), and a little more than one-third were older than 65. Approximately 75 had chronic liver disease.
Overall, 955 patients were given acetaminophen in doses exceeding the 4-g/day limit. This represents 4% of the entire hospitalized population and 6.6% of the cohort of patients given any acetaminophen, the researchers said (Arch. Intern. Med. 2012 [doi:10.1001/2013.jamainternmed.438]).
Each patient who received supratherapeutic dosing had a mean of five such incidents during the course of a mean of 3 days. Instances of such overmedicating ranged as high as 48 separate occasions over the course of 30 days.
Approximately 40% of the 955 patients received supratherapeutic dosing for 3 or more days, and 4% received it for 10 or more days.
"Our findings show that despite policies and procedures to monitor and control patients’ acetaminophen exposure, the incidence of supratherapeutic acetaminophen dosing in hospitalized patients remains high," Dr. Zhou and her associates said.
Previous studies have shown that many physicians and nurses aren’t aware of the maximal recommended daily dosing of acetaminophen, and that many have some difficulty identifying which products contain the agent. Therefore, increased training is warranted "to help clinicians identify acetaminophen-containing products and monitor closely the daily dose of acetaminophen," the investigators said.
A reassessment of long-accepted dosing regimens may also be warranted, "especially the scheduled use of products containing 500 mg of acetaminophen," they added.
The study was funded by the Partners-Siemens Research Council. The investigators reported no relevant financial conflicts.