%D 2024
%R doi:10.1136/bmjopen-2024-091789
%N 12
%T Novel prehospital lactate cut-off estimation for mortality: a multicentre observational study
%A Francisco Martín-Rodríguez
%A Ancor Sanz-Garcia
%A Daniel Zalama-Sánchez
%A Pedro Ángel de Santos Castro
%A Eduardo René Silva Alvarado
%A Santos Gracia Villar
%A Luis Alonso Dzul López
%A Silvia Aparicio Obregón
%A Rubén Calderón Iglesias
%A Carlos del Pozo Vegas
%A Raúl López-Izquierdo
%V 14
%P e091789
%L uneatlantico15984
%X Objectives: Point-of-care testing available in prehospital settings requires the establishment of new medical decision points. The aim of the present work was to determine the cut-off of the lactate threshold that activates alert triggers for all-cause 2-day mortality.

Design: Multicentre, prospective, ambulance-based, observational study.

Setting: Patients treated via emergency medical services (EMSs) and delivered to the emergency department between 2019 and 2023 were selected in Spain.

Participants: Adults with any acute disease.

Primary and secondary outcome measures: Epidemiological data, vital signs and prehospital point-of-care glucose and lactate levels were obtained. The outcome was all-cause 2-day in-hospital mortality. The cut-offs were obtained via three different methods: (i) indirect (which considers survivors and non-survivors), direct (which considers only survivors) assessment and lactate quartile. Additionally, the quartile approach was used to determine the differences in lactate distribution between survivors and non-survivors. Three different back-to-back studies with the same methodology were used.

Results: A total of 11 713 patients fulfilled the inclusion criteria. The mortality rate was 4.6% (542 patients). The difference in the median prehospital lactate concentration (mmol/L) between survivors and non-survivors was statistically significant (p<0.001): 2.29 (95% CI 1.43 to 3.38) and 7.14 (95% CI 5.11 to 9.71), respectively. Globally, the cut-off for all the studies combined was estimated by the direct method to be 3.71 mmol/L (95% CI 2.92 to 3.91), which was similar to the indirect value of 3.07 (95% CI 2.95 to 5.49) and the third quartile of 4.00. The mortality rate in patients who were less than 3.71 mmol/L was 0.004%, and that above that cut-off was 18%.

Conclusions: This study established a real-world lactate cut-off for 2-day in-hospital mortality of 3.71 mmol/L (95% CI 2.92 to 3.91) on the basis of data from the EMS. Considering this cut-off point could improve patient management via EMS services, allowing quick identification of patients at high risk of clinical worsening.
%J BMJ Open