Sugammadex in anaphylaxis – a case‐control study? A reply

We thank Dr. Whitehead for his interest in our paper 1 and his acknowledgement that the publication is timely with the 6th National Audit Project (NAP6) study on anaphylaxis underway. However, we disgree with Dr. Whitehead's comments about our design and conclusions. We compared cases of anaphylaxis treated with sugammadex and subsequently confirmed to be triggered by rocuronium, with those not triggered by rocuronium. The purpose of the comparison was to be able to determine by implication whether sugammadex can be relied upon as an effective treatment in anaphylaxis by modifying the immunological cascade of a suspected hypersensitivity reaction. As there appeared to be no obvious difference in the frequency of confirmed rocuronium-induced anaphylaxis by response to treatment with sugammadex, we had to conclude that this was not the case. Our study was a case-control study insofar as we compared patients with a known pre-specified outcome (improvement in blood pressure after the administration of sugammadex (cases) vs. no improvement (controls)), and then determined the frequency of confirmed rocuronium-induced anaphylaxis in these two groups (3/6 vs 5/7, respectively). Dr. Whitehead is correct that the controls were a subset of patients in whom sugammadex had been administered in an attempt to modify the course of rocuronium-induced anaphylaxis. However, we disagree with him that this was an inappropriate methodology. All the anaesthetists referring cases for analysis felt that they were dealing with rocuronium-induced anaphylaxis and administered sugammadex. Some of the anaphylaxis cases were subsequently found to be not rocuronium-based, or not anaphylaxis, and were treated as controls. We are unclear how to improve this methodology to search for and select suitable controls. We do not agree with Dr. Whitehead's criticism of the peer-review process. We were very appreciative of the peer review we received, including the many helpful comments, and were grateful for the opportunity to publish this information on the apparent lack of efficacy of sugammadex in the management of rocuronium-induced anaphylaxis. This is consistent with in-vivo experiments and a rational appraisal of the pathophysiology of anaphylaxis 2, 3. This is the first study that has examined the efficacy of sugammadex in presumed anaphylaxis that includes a control group. As we provided all our data in a summary table, as well as comprehensive case details in the online version of the article, readers will be able to formulate their own conclusions.