β-Lactam Therapeutic Drug Monitoring in Critically Ill Patients

To the Editor—We write in response to the systematic review by Mangalore et al [1] on β-lactam therapeutic drug monitoring (TDM) in critically ill patients. With the ever-growing interest in TDM, and varying opinions on its utility, we commend the authors’ endeavor to report on patient important clinical outcomes. Their cumulative results highlight the largest barrier to implementation: no demonstrable benefit toward patient mortality or length of stay. Around the same time, Ewoldt et al [2] published the DOLPHIN trial, a randomized controlled trial comparing model-informed precision dosing of β-lactams and ciprofloxacin to standard dosing in critically ill patients. They also reported an insignificant benefit of TDM on intensive care unit length of stay and morality. To summarize the findings of both recent studies, we recreated the mortality meta-analysis from Mangalore et al and included the new β-lactam-specific data from Ewoldt et al. Data from studies included in the meta-analysis by Mangalore et al were extracted. The β-lactam data by Ewoldt et al (personal communication, T. Ewoldt, 6 February 2023) were added to the data file and reanalyzed (Figure 1) using random effects meta-analysis modeling on SPSS version 29 software.