Association between lactate determined at emergency department arrival and the probability of inhospital mortality and intensive care admission in elderly patients.

Background and importance: Elderly patients often have atypical clinical presentations. Lactate measurement on arrival at the Emergency Department (ED) could be useful to identify elderly patients with a bad prognosis.

Objective: The study aimed to investigate the relationship between serum lactate determined at ED arrival and the probability of inhospital mortality and intensive care (ICU) admission in elderly patients.

Design: Retrospective multipurpose registry. Secondary analysis of the EDEN cohort (Elderly Department and Elder Needs).

Settings and participants: All patients ≥65 years attending 52 Spanish EDs during 2 week and in whom serum lactate was determined at ED arrival.

Outcome measures and analysis: The relationship between serum lactate values and the risk of inhospital all-cause death and transfer from the ED to the ICU was assessed by unadjusted and adjusted logistic regression assuming linearity and restricted cubic spline models assuming nonlinearity.

Results: The cohort included 25 557 patients. The 3024 patients in whom lactate was measured were analyzed. The median age was 81 years (74-87), 1506 (27.2%) were women, 591 (19.5%) had serious comorbidities, 475 (15.7%) severe dependency, and 648 (21.4%) dementia. Death occurred during hospitalization in 217 patients (7.2%) and 53 patients (1.75%) were admitted to the ICU. Serum lactate values were nonlinear related to inhospital mortality and ICU admission. Serum lactate >3.1 mmol/L [odds ratio (OR): 1.60, 95% confidence interval (CI): 1.02-2.50] for inhospital mortality and 3.2 mmol/L (OR: 2.83, 95% CI: 1.03-6.79) for ICU admission were associated with significantly increased ORs in the adjusted models.

Conclusion: Serum lactate measured at ED arrival has a significant and exponential relationship with inhospital mortality and ICU admission in elderly patients.