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Comment & Response
July 16, 2019

Intravenous Acetaminophen for Postoperative Delirium—Reply

Author Affiliations
  • 1Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
JAMA. 2019;322(3):272. doi:10.1001/jama.2019.6134

In Reply We agree with Dr Wanek that the fentanyl conversion factor for morphine equivalents was incorrect. A conversion factor of 2.4 was used per current recommendations1 for conversion of fentanyl transdermal patch dosage in micrograms per hour to morphine equivalents in milligrams per day. Cardiac surgical patients in this trial received IV fentanyl; therefore, the correct conversion factor for fentanyl in an opioid-naive patient is 100 (ie, 100 µg of fentanyl = 10 mg of morphine). We recalculated additional postoperative analgesic requirements as the sum of (fentanyl dose × 100) + (hydromorphone dose × 4) + morphine dose + (oxycodone dose × 1.5) morphine milligram equivalents. In the original article, the median opioid dose was 322.5 µg in the acetaminophen groups and 405.3 µg in the placebo groups (difference, −83 µg; 95% CI, −154 to −14 µg; P = .02). Using the revised formula, the acetaminophen groups still received a lower opioid dose in the first 48 hours postoperatively compared with the placebo groups (median, 10 082.5 µg vs 12 609.0 µg; difference, −2530.0 µg; 95% CI, −5064 to −22 µg; P = .03), which was statistically significant. The article has been corrected online.