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Incidence and risk factors for hyperlactatemia in ED patients with acute metformin overdose

Taub ES, Hoffman RS, Manini AF

The American journal of emergency medicine, 2019

Abstract

INTRODUCTION: The goals of this study are to describe clinical characteristics and risk factors for metabolic acidosis with hyperlactatemia in emergency department (ED) patients with acute metformin overdose.

METHODS: This was a secondary analysis of data from a retrospective observational cohort of adult ED patients presenting with acute drug overdose at two tertiary care hospitals over 5 years. The primary outcomes were: (1) hyperlactatemia, defined as a lactate concentration ≥ 2 mmol/L at any point during hospital admission and, (2) metformin associated lactic acidosis (MALA), defined as a lactate concentration ≥ 5 mmol/L and pH <7.35 at any point during hospital admission.

RESULTS: We screened 3739 acute overdoses; 2872 met eligibility, 56 self-reported metformin overdose (57% female, mean age 55.8). Of these, 39 had measured lactate values. There was a high incidence of hyperlactatemia (56.4%); MALA was less frequent (17.9%). There were no deaths. Low serum bicarbonate was an independent clinical risk factor for hyperlactatemia (adjusted p < 0.05). Acetaminophen co-exposure was an independent clinical risk factor for MALA (OR 24.40, 95% CI 1.6-376.4).

CONCLUSIONS: In ED patients with acute metformin overdose, initial hyperlactatemia is common but MALA is unusual. Acetaminophen co-exposure is a novel independent risk factor for the occurrence of MALA that deserves further investigation.

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Evidence Hub reads this as a case-control, done in people. Its evidence level is 4 of 5 (Low · observational). Observational designs can show an association but not prove cause.

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