To the Editor:

We have read with great interest the recent article by Kheterpal et al.,1  indicating that sugammadex may be associated with a lower incidence of postoperative pulmonary complications, compared with neostigmine, when used for reversal of neuromuscular blockade in adults.

With a comprehensive matching approach, Kheterpal et al. successfully balanced demographic, procedural, and intraoperative factors between groups. However, given the 5-yr study period and a median time difference of 29 months between the neostigmine and sugammadex groups, we contend that it is critical to include an examination of the trend of complications over time informed by the date of intervention, which could be achieved by an interrupted time series analysis.

Numerous studies have demonstrated substantial changes in postoperative pulmonary complication rates over time.2–4  Although the authors take steps to account for temporal bias, including matching cases and controls that were within 24 months of one another, this may be inadequate. In light of these and other findings, we question whether temporal trends may still be biasing the authors’ findings.

Competing Interests

Dr. Freundlich has received grant funding and consulting fees from Medtronic (Minneapolis, Minnesota) for work unrelated to the content of this letter. Dr. Freundlich also holds stock in 3M (St. Paul, Minnesota) and Johnson & Johnson (New Brunswick, New Jersey). The remaining authors declare no competing interests.

Research Support

Dr. Freundlich is supported by ongoing grant No. 1KL2TR002245 from the National Institutes of Health, National Center for Advancing Translational Sciences (Bethesda, Maryland).

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