When the model does not fit the data, the model is wrong.

摘要

To the Editor:-Piihringer et al. provide convincing evidence that sugammadex speeds the reversal of rocuronium and that the benefit increases with dose. Four figures display time to 90% train-of-four recovery as a function of sugammadex dose; in addition to raw data, each figure displays a curve based on fitting an exponential model to the data. Unfortunately, these curves provide misleading information about the dose-effect relationship. In that increasing the sugammadex dose should decrease (or not change) recovery time, the exponential model has the correct form (monotonic nonincreasing) but the wrong shape (as evidenced by its failure to match the data at low doses).The authors' intent in fitting this curve is to allow claims independent of the data. For example, based on their figure 1, one might claim that "following a dose of 2 mg/kg, time to 90% train-of-four is expected to be 30 min." Yet, this claim is not supported by the data. Similarly, any claim about the expected response at doses not studied cannot be inferred from the curve drawn by the investigators.