Prognostic accuracy of using lactate in addition to the quick Sequential Organ Failure Assessment score and the National Early Warning Score for emergency department patients with suspected infection

Background The aim of this study was to determine whether: (1) the quick Sequential (Sepsis-related) Organ Failure Assessment (qSOFA) and National Early Warning Score (NEWS) clinical prediction tools alone, (2) modified versions of these prediction tools that integrate lactate into their scores, or (3) use of the two tools in tandem with lactate better predicts in-hospital 28-day mortality among adult EDpatients with suspected infection. Methods From 1 January through 31 December 2018, this retrospective cohort study enrolled consecutive adult patients with suspected infection evaluated at two EDs in France. Patients were included if blood cultures were obtained and non-prophylactic antibiotics were administered in the ED. qSOFA, NEWS criteria and lactate measurements were recorded when patients were clinically suspected of having an infection. Two composite scores (lactate qSOFA (LqSOFA) and lactate NEWS (LNEWS)) integrating lactate were created. Diagnostic test performances for predicting in-hospital mortality within 28days were assessed for qSOFA≥2, LqSOFA≥2, qSOFA≥2 or lactate≥2 mmol/L, and for NEWS≥7, LNEWS≥7, and NEWS≥7 or lactate≥2 mmol/L. Results 1003 patients were included, 130 (13%) of whom had died by day 28. Sensitivities for 28-day mortality were 50% (95%CI41% to 59%) for qSOFA≥2,69% (95% CI60% to 77%) for LqSOFA≥2,77% (95% CI69% to 84%) for qSOFA or lactate≥2 mmol/L; and 69% (95% CI60% to 77%) for NEWS≥7, 80% (95% CI72% to 86%) for LNEWS≥7, 87% (95% CI80% to 92%) for NEWS≥7 or lactate≥2 mmol/L. Conclusion Lactate used in tandem with qSOFA or NEWS yielded higher sensitivities in predicting in-hospital 28-day mortality, as compared with integration of lactate into these prediction tools or usage of the tools independently.