Clinical decision-making for patients admitted to the emergency department for acute drug overdose — particularly from drugs that include opioids and acetaminophen — may be facilitated by measuring initial lactate concentration, according to a study published in the Annals of Emergency Medicine.

This observational study was conducted over a 5-year period in the high-volume emergency departments of 2 university hospitals. The serum lactate levels of 1406 adults (mean age, 43.1 years) admitted for acute drug overdose were measured. In-hospital all-cause fatality and the occurrence of shock (ie, treatment with vasopressors) during emergency department or hospital stay were the study’s primary and secondary outcomes, respectively.

Of the 1406 patients analyzed, 24 (1.7%) died during emergency department or hospital stay. These patients had a greater mean initial lactate concentration compared with survivors (8.1±1.6 mmol/L vs 2.21±0.08 mmol/L, respectively; 95% CI, 3.4-8.1 mmol/L; P <.001). The optimal lactate concentration cut point for in-hospital mortality was 5.0 mmol/L (odds ratio [OR], 34.2; 95% CI, 13.7-84.2). This cut-off had 94.7% specificity and 70.8% selectivity. The optimal lactate concentration cut point for a combination of fatality and shock was 2.7 mmol/L (OR 7.9; 95% CI, 4.5-13.9).

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The top 3 drug classes associated with overdose-related fatality were digoxin (21.1%; OR 18.2; P <.001), diuretics (16.7%; OR 12.4; P =.02), and β-adrenergic antagonists/calcium channel blocker combinations (11.9%; OR 10.5; P <.001).

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The predictive value of initial lactate concentration for fatality was highest with salicylate (area under the curve [AUC], 0.98; 95% CI, 0.90-1.0; cut point, 6.0 mmol/L), sympathomimetic drugs (AUC, 0.98; 95% CI, 0.95-0.99; cut point, 7.8 mmol/L), acetaminophen (AUC, 0.98; 95% CI, 0.95-1.0; cut point, 10.0 mmol/L), opioids (AUC, 0.97; 95% CI, 0.94-0.99; cut point, 3.1 mmol/L), digoxin (AUC, 0.92; 95% CI, 0.78-1.0; cut point, 2.4 mmol/L), and anticonvulsant medications (AUC, 0.91; 95% CI, 0.76-1.0; cut point, 3.0 mmol/L).

A limitation of this analysis is that the time elapsed between emergency department admission and measurement of lactate concentration was not recorded.

“The initial [emergency department] lactate concentration might be used as a biomarker that can aid early decision-making [for patients presenting with drug overdose],” concluded the study authors.

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Cheung R, Hoffman RS, Vlahov D, Manini AF. Prognostic utility of initial lactate in patients with acute drug overdose: A validation cohort [published online April 6, 2018]. Ann Emerg Med. doi: 10.1016/j.annemergmed.2018.02.022