Cheung R, et al. - This cohort study was planned to formally validate the prognostic utility of the initial lactate concentration for inhospital mortality from acute drug poisoning in a larger, distinct patient population with acute drug overdose. Findings suggested that in Emergency Department (ED) patients with acute drug overdose, initial lactate concentration is a useful biomarker for early clinical decisionmaking.

Methods

• Researchers conducted an observational, prospective, cohort study during 5 years at 2 urban teaching hospitals.
• They tested serum lactate levels in consecutive adult ED patients with acute drug overdose as part of clinical care.
• Inpatient fatality was assessed as the primary outcome.
• To determine optimal cut points, test characteristics, area under the curve, odds ratios, and 95% confidence intervals (Cis), they plotted receiver operating characteristics.

Results

• Researchers screened 3,739 patients.
• Of these, 1,406 were analyzed (56% women; mean age 43.1 years) and 24 died (1.7%).
• They noted that the difference in mean initial lactate concentration was 5.9 mmol/L (95% CI 3.4 to 8.1 mmol/L) higher in patients who died compared with survivors.
• For prediction of fatality, the area under the curve was 0.85 (95% CI 0.73 to 0.95).
• For fatality, the optimal lactate cut point was greater than or equal to 5.0 (odds ratio 34.2; 95% CI 13.7 to 84.2; 94.7% specificity).
• Drug classes for which lactate showed the greatest utility included salicylates, sympathomimetics, acetaminophen, and opioids (all area under the curve ≥0.97); the lowest utility was shown for diuretics and angiotensin-converting enzyme inhibitors.