Association between prehospital lactate categories with short- and long-term mortality: a prospective, observational multicenter study.

ABSTRACT

BACKGROUND: Lactate is an already recognized biomarker for short-term mortality in emergency medical services (EMS). However, how different levels of lactate are associated with short-, mid- and long-term outcomes should be unveiled. AIM: To determine how different categories of hyperlactatemia are associated with mortality. We also aim to clinically characterize hyperlactatemia groups. DESIGN: A multicenter, prospective, observational study performed between January 2019 and February 2022, considering 48 basic life support units and 5 advanced life support units referring to 4 tertiary care hospitals (Spain). Patients were recruited from phone requests for emergency assistance in adults, evacuated to emergency departments. The primary outcome was in-hospital mortality from any cause within the first to the 365-day period following EMS attendance. The main measures were demographical and biochemical variables, prehospital advanced life support techniques used and patient condition categorized in 24 diseases. METHODS: Univariate and Cox regression analysis. RESULTS: A total of 5072 participants fulfilled inclusion criteria. Group #1 (non-hyperlactatemia) was composed of 2389 subjects (47.1%), Group #2 (mild hyperlactatemia) of 1834 (36.1%), Group #3 (hyperlactatemia) of 333 (6.6%) and, finally, Group #4 (severe hyperlactatemia) of 516 (10.2%). The 1-day mortality was 0.2%, 1.1%, 9% and 22.3% in the four lactate groups, respectively. Long-term mortality (365 days) was 10.2%, 22.7%, 38.7% and 46.7% in the four lactate groups, respectively. Differences between patients' conditions of lactatemia groups were also found. CONCLUSIONS: Our results demonstrated that prehospital lactate categories were associated with short- and long-term outcomes in a different manner. These results will allow EMS to establish different risk states according to the prehospital lactate categories.