Intravenous acetaminophen does not have an opioid sparing effect in Emergency Department patients with painful conditions

Background: Pain in the Emergency Department is common and is frequently treated with opioids. Due to the opioid epidemic, it is clinically helpful to decrease opioid usage. The purpose of this study was to evaluate opioid requirement in Emergency Department patients with painful conditions who receive intravenous acetaminophen. Methods: In this prospective cohort study, patients aged 18 years and older and treated with opioids in the acute phase were included. Patients receiving additional intravenous acetaminophen were compared to patients who did not. Primary outcome was opioid requirement, measured in Morphine Equivalent Units (MEU) during Emergency Department stay. Secondary outcomes were opioid requirement after discharge; decrease in pain scores; occurrence of adverse events and patient satisfaction. Results: A total of 116 patients were included of whom 76 received intravenous acetaminophen. Opioid consumption in the acute phase was not significantly different (p=0.53) between patients receiving (10.0 MEU (IQR 7.5; 15.0)) and those not receiving acetaminophen: 10.0 MEU (IQR 7.1; 15.0). After discharge these numbers were 15.0 MEU (IQR 7.5; 30.0) versus 30.0 MEU (IQR 15.0; 43.8), respectively (p=0.059). In both groups median NRS pain scores decreased from 9.0 to 4.0 and >80% of patients were satisfied regarding pain treatment. Nine minor adverse events were recorded, equally divided among the groups. Conclusions: The additional use of intravenous acetaminophen did not decrease opioid requirement in adult patients with acute pain during Emergency Department stay. There was a trend towards decreased opioid requirement during 24 h after discharge.