Can full-stay lactate burden predict ICU mortality? The importance of a defined prediction time

Deininger and colleagues reported that time-weighted average lactate calculated over the entire intensive care stay was strongly associated with mortality after traumatic brain injury. This finding supports full-stay TWAL as a summary of sustained lactate exposure; however, because the measure cannot be finalized before death or discharge, it does not establish prospective prognostic performance from a predefined, clinically actionable time. The 72-h analysis also represents conditional prognosis among patients remaining under intensive care at that landmark. The incremental value of time weighting over mean lactate remains uncertain, and performance estimated in an outcome-matched subset may not generalize to a consecutive population. A prespecified landmark framework would better define the clinical prognostic value of longitudinal lactate indices.