In Reply:
We would like to thank Pereira et al.1 for their interest and comments related to our article.2 In their letter, the authors state that the reduction in sugammadex use could have been the result of better monitoring equipment and/or a reduction in general anesthetics with neuromuscular blockade. While data on use of monitoring equipment was not collected, the number of general anesthetics and administrations of neuromuscular blocking drugs was presented in table 1 of the original article. The statistical analyses in Supplemental Digital Content 2 (http://links.lww.com/ALN/C45), supplemental tables 1 and 2, showed that the slope and level changes were not statistically significant, suggesting that general anesthetics with neuromuscular blockade were relatively unchanged after implementation of the cognitive aid.
The authors also ask why quantitative monitors were not selected for acquisition. In fact, our anesthesiologists did request the purchase of quantitative monitors, but this request was not approved. A recent article notes that the new product acquisition process is typically governed by a value analysis committee, which Engelman et al.3 state compares short-term costs rather than long-term value. The final choice of qualitative monitors may have been the result of such an approach, where institutional purchasing decisions are beyond the control of the providers.
The authors also note that the number of neostigmine administrations was not presented and that increased use of neostigmine might increase costs postintervention. In fact, the costs associated with neostigmine were part of the secondary outcome, total acquisition costs of neuromuscular blocking drugs and reversal agents, which decreased postintervention.
The authors go on to suggest that the finding of the postintervention monthly rate of sugammadex administrations (4 per 1,000 general anesthetics with a nonsignificant P value) contradicts the figures. In figure 2 in the original article, upper left panel showing sugammadex, the solid trend line to the right of the vertical gray area (intervention period) appears flat. A nonsignificant P value for the postintervention slope indicates that the slope is in fact flat, or not different from zero. Only a nonzero value for this postintervention slope would indicate that sugammadex use was increasing after the intervention. Our figure demonstrates that after implementation of the cognitive aid, the immediate decrease in sugammadex use was sustained in the postintervention period.
Finally, the authors note that the regression of the interrupted time series analysis seems to be less fitted when evaluating adverse respiratory events. While this is true, we did not find the parameter coefficients to be statistically significant.
In summary, because time series analyses are not used very commonly in the scientific literature, it may be challenging for many clinicians to interpret the results. Ultimately, the purpose of this statistical analysis is to demonstrate whether the slope and level of an outcome have changed over time. A more detailed explanation of the interrupted time series analysis can be found in a recent article by Mascha and Sessler.4
Competing Interests
Dr. Schumann reports an ongoing financial relationship with Wolters Kluwer Publishers (Philadelphia, Pennsylvania). The other authors declare no competing interests.
