Objective: To evaluate the use of antidotal therapy in patients with an elevated digitalis concentration following chronic or acute exposure.
Design and setting: Retrospective review of patient records over 2 years in 20 city hospitals in France.
Patients: Overall 838 patients with an elevated serum digitalis concentration (digoxin > 1.95ng /ml or digitoxin > 23ng /ml) were included in the study. Of these, 67 (8%) had received antidotal therapy with Fab fragments.
Measurements and results: The relationships between previously reported prognostic criteria and use of antidotal therapy were investigated. We identified five independent factors that were associated with the use of antidotal therapy: acute overdose (OR 15.74), Fab fragment availability in the hospital (11.06), serum potassium (1.81), and heart rate (0.96). Mortality was significantly lower in Fab-treated (6%, 4/67) than untreated patients (15%, 117/770).
Conclusions: Antidotal therapy is underused in patients with an elevated digitalis concentration especially in patients with chronic digitalis exposure. These patients in our series presented a higher mortality rate than patients with acute poisoning. Although they were older and tended to have a history of cardiac disease, they did not differ from patients with acute poisoning with regard to the main severity criteria and prognostic factors. The use of identical criteria for antidotal treatment after acute and chronic poisoning should help optimize outcomes. Fab fragment availability is insufficient in France but ranks only second after type of poisoning (acute or chronic) in the multivariate association with Fab treatment.