Intravenous Acetaminophen -an Ineffective Analgesic?

To the Editor:Wang et al. reported in the December 2015 issue of Pu0026T 1 that patients after bariatric surgery administered intravenous (IV) acetaminophen required higher doses of opioids in the postoperative period than patients on opioids alone. We would like to comment on two points necessitating a discussion.First, the findings of the presented, small, retrospective study (N = 96) are in conflict with several large meta-analyses, including many prospective randomized trials with thousands of patients.2–4 Possible explanations could include: 1) different bariatric surgical procedures; 2) unchanged opioid prescribing practices after IV acetaminophen was added to the hospital’s formulary; and 3) noncompliance to American Society of Anesthesiologists practice guidelines to schedule acetaminophen and nonsteroidal anti-inflammatory drugs around the clock unless contraindicated.5Second, Wang et al. did not summarize the four retrospective studies presenting data on a similar patient population (morbidly obese patients undergoing bariatric surgery), including approximately 900 patients, all showing a reduction of opioid consumption in the postoperative period with the addition of IV acetaminophen.6–9We believe that it would be more relevant to try to interpret the study results in light of overwhelming high-quality research. We are interested as to why the results of this small study differ from the results of the prior studies. A possible explanation could be bias and methodological deficiencies that are inevitable in a retrospective analysis.