Heart rate-corrected QT interval predicts mortality in glyphosate-surfactant herbicide-poisoned patients

Glyphosate-surfactant herbicide is promoted by the manufacturer as having no risks to human health. Glyphosate surfactant has recently been used with increasing frequency in suicide attempts, so clinical toxicologists occasionally encounter cases of severe systemic toxicity. The purpose of this study was to identify the early predictive factors of patients at risk for mortality and the usefulness of the corrected QT interval (QTc interval) for predicting mortality from glyphosate-surfactant intoxication.

This was a retrospective cohort study conducted from January 2005 to December 2012. A total of 153 patients with acute glyphosate-surfactant ingestion were included. To identify the predictive factors for mortality, objective variables easily assessed at presentation including previously reported predictive factors for mortality and severity were retrospectively analyzed for their association with mortality using univariate and multiple logistic analyses.

The average age of the patients was 56 years (range, 19-93 years). Of the 153 patients, 19 (12.4%) died. The most common abnormal electrocardiogram findings were prolonged QTc interval followed by intraventricular conduction delay and first-degree atrioventricular block. Nonsurvivors had a significantly more prolonged QTc interval when compared with that of survivors (survivors: 453.4 ± 33.6 milliseconds vs nonsurvivors: 542 ± 32.0 milliseconds, P < .001). Corrected QT interval and age were associated with a significantly increased risk of death in a multiple logistic regression. In a receiver operating curve analysis, the QTc interval had significant discriminatory power.

Prolonged QTc interval seems to be a useful prognostic factor for mortality in patients intoxicated with glyphosate-surfactant herbicide.