Comparison of risk-adjustment methods to predict in-hospital mortality among emergency department patients admitted to critical care settings

Abstract Objective The clinical interpretation of lactate ≤ 2.00 mmol/L in emergency department (ED) patients is not well characterized. This study aims to determine the optimal cutoff value for lactate within the reference range that predicts in-hospital mortality among ED patients with initial serum lactate levels within the reference range. Methods This was a retrospective study of adult patients presenting to a tertiary ED between the dates of January 1, 2014 and June 30, 2019 with an initial serum lactate level less than 2.00 mmol/L. The primary outcome was in-hospital mortality. Youden’s index was utilized to determine the optimal threshold that predicts mortality. Patients above the threshold were labeled as having relative hyperlactatemia. A multivariate logistic regression was performed to determine the association between relative hyperlactatemia and in-hospital mortality. Subgroup analyses were done to further examine the interaction between relative hyperlactatemia and hospital mortality. Results During the study period, 1638 patients were included. The mean age was 66.9 ± 18.6 years, 47.1% of the population were female, and the most prevalent comorbidity was hypertension (56.7%). The mean lactate level at presentation was 1.5 ± 0.3 mmol/L. In-hospital mortality was 3.8% in the overall population and 16.2% were admitted to the ICU. A lactate of 1.33 mmol/L was found to be the optimal cutoff that best discriminates between survivors and non-survivors. Relative hyperlactatemia was an independent predictor of in-hospital mortality (OR 1.78 CI1.18-4.03; p 0.02). Finally, Relative hyperlactatemia was associated with increased mortality in patients without hypertension (4.7% versus 1.1%; p 0.008), as well as patients without diabetes or COPD. Conclusion The optimal cutoff of initial serum lactate that discriminates between survivors and non-survivors is in the ED 1.33 mmol/L. Relative hyperlactatemia is associated with increased mortality in emergency department patients, and this interaction seems to be more important in healthy patients.

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Evaluation of the Prognostic Value of Lactate and Acid-base Status in Patients Presenting to the Emergency Department

10.21203/rs.3.rs-92196/v1 ◽

2020 ◽

Author(s):

Ramiro D'Abrantes ◽

Laura DUNN ◽

Tim MCMILLAN ◽

Ben CORNWELL ◽

Ben BLOOM ◽

...

Keyword(s):

Emergency Department ◽

Hospital Mortality ◽

Predictive Value ◽

Point Of Care ◽

Acid Base ◽

Wide Range ◽

Acid Base Status ◽

Emergency Department Patients ◽

Lactate Levels ◽

High Lactate

Abstract IntroductionPoint-of-care metabolic screens are frequently used in the assessment of critical illness. Lactate levels predict mortality in a wide range of patients presenting to the Emergency Department but the effect of co-existing acidosis is unknown. We investigated the effect that acidosis has on in-hospital mortality for patients with hyperlactataemia. Methods This is a retrospective cohort study. The inclusion criteria were patients over 17 years of age who received a metabolic panel on arrival to the resuscitation area of the Emergency Department. The primary outcome was in-hospital mortality. The groups were normal lactate (0.0-2.0 mmol/L), intermediate lactate (2.1-4.0 mmol/L) and high lactate (>4.0 mmol/L), with and without acidosis. Odds ratios (OR) were calculated to assess the differences in mortality rates between groups stratified by lactate and acid-base status.Results 4107 metabolic panels were collected and 3238 were assessed. 510 (15.8%) & 784 (24.2%) patients had a normal lactate and acidosis or no acidosis respectively. 587 (18.1%) & 842 (26.0%) patients had intermediate lactate and acidosis or no acidosis respectively. 388 (12.0%) & 127 (3.9%) patients had high lactate and acidosis or no acidosis respectively. The overall mortality was 5%. In normal lactate group mortality was 4.3% and 0.6%, intermediate lactate mortality was 5.6% and 2.6%, and high lactate group mortality was 19.3% and 3.9%, with and without acidosis respectively. Combining base excess < -6 and lactate >4 mmol/L had a sensitivity of 39%, specificity of 96%, positive predictive value of 32% and a negative predictive value of 98% for in-hospital mortality, OR 14.0 (95% CI 9.77 – 20.11). Conclusion In an undifferentiated cohort of Emergency Department patients presenting to the resuscitation area lactaemia associated with acidosis is a more accurate predictor of in-hospital mortality than hyperlactataemia.

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