Comparison of Initial Lactate Levels and Their Prognostic Utility in Obese and Nonobese Patients with Sepsis

Sepsis is a high morbidity and mortality disease that is highly prevalent in emergency departments (EDs). Lactate is often utilized as a biomarker for sepsis, though its performance among subgroups such as obese patients is not well characterized. Given existing data on differences in lactate metabolism at baseline between obese and nonobese patients, this may be clinically relevant in sepsis identification and prognostication.

We sought to compare differences in initial lactate measurements and lactate utility in predicting 30-day mortality between obese and nonobese body mass index (BMI) patients with vasopressor-dependent and non-vasopressor-dependent sepsis.

We performed a retrospective cohort study of obese and nonobese patients presenting to an adult hospital ED with sepsis with organ dysfunction. Patients were separated into vasopressor-dependent or non-vasopressor-dependent groups. The primary outcomes were differences in initial lactate and utility of initial lactate in predicting 30-day all-cause mortality by employing receiver operator characteristic curves.

Obese patients had lower initial lactate (2.2 mmol/L) compared with nonobese patients (2.4 mmol/L) in the non-vasopressor-dependent cohort. Lactate performed poorly-to-moderately well as a biomarker for 30-day mortality between obese and nonobese patients with sepsis, with no differences between BMI groups.

Initial lactate levels are lower in obese patients compared with nonobese patients, but are unlikely to be clinically significant. We found no difference in lactate's utility as a biomarker for prediction of 30-day all-cause mortality between obese and nonobese patients. Lactate overall maintains some utility as a predictor of sepsis mortality, though factors that contribute to lactate levels remain unclear.