Failure of Risk Assessment After Paracetamol Overdose—A Short Communication

Abstract

Background:The accepted treatment for patients with acetaminophen/paracetamol overdose includes risk assessment based on the Rumack-Matthew (R-M) nomogram. An inaccurate use of the nomogram may result in improper treatment. Clinicians were surveyed to determine their understanding and proper use of this risk assessment tool in practice.Methods: Differences between visual risk assessment using the same depiction of the R-M nomogram and calculated risk assessment were determined using an online calculator developed based on the Rumack equation. An online survey was administered in French between August 25, 2021, and November 25, 2021, as a Google Form with 14 questions (the paracetamol concentration and time postingestion were stated). A total of 147 respondents with an average age of 32 years (range 23-61 years) performed risk assessment (low/possible/probable/not assessable). The mean assessment accuracy was 66.2 6 26.7% (12.3-99.3). The sensitivity, specificity, positive predictive value, and negative predictive value were 93%, 55%, 71%, and 89%, respectively. A subcohort of n = 31 senior clinicians showed the same trends (91%, 52%, 69%, and 84%).Results: Approximately 7% of patients who are at risk of hepatotoxicity based on the R-M nomogram would not be treated. By contrast, N-acetylcysteine was not recommended by the R-M nomogram but would be administered to approximately 50% of patients. A concern for the latter group is that anaphylactoid reactions occur in up to 25% of patients with low paracetamol concentrations.Conclusions: Some patients may be undertreated, resulting in possible hepatotoxicity, and many patients may be overtreated, resulting in a high percentage of anaphylaxis. Rather than relying on visual risk assessment, physicians should use an online calculator (www.hopitox.com/?lang=en) or consult with a toxicologist or poison center to substantially improve patient care after acetaminophen/paracetamol overdose.

Paracetamol (acetaminophen) poisoning: The early years

“…According to a recent survey, the nomogram is not always used correctly and the use of an online calculator has been recommended. 22 In the UK, the nomogram treatment line was initially set at 200 mg/L at 4 h 23 while, under pressure from the Food and Drug Administration, a lower line corresponding to 150 mg/L at 4 h was used in the USA. 18,24 In 2012, on the recommendation of the UK Commission on Human Medicines the treatment line was lowered to 100 mg/L at 4 h. As a result, there was a large increase in admissions, many more patients were treated with NAC and more suffered adverse reactions to it.…”

“…In addition, there may be difficulties with staggered (repeated) overdoses. According to a recent survey, the nomogram is not always used correctly and the use of an online calculator has been recommended 22 . In the UK, the nomogram treatment line was initially set at 200 mg/L at 4 h 23 while, under pressure from the Food and Drug Administration, a lower line corresponding to 150 mg/L at 4 h was used in the USA 18,24 .…”