Appropriateness of digoxin measurement in hospitalized patients

Measurement of serum digoxin concentrations before steady-state is reached results in a falsely low concentration, and may affect treatment safety. We evaluated the proportion of serum digoxin measurements performed before steady-state is reached and the reasons for inappropriate sampling in hospitalized patients.

Electronic medical records of patients hospitalized between January 2011 and December 2015 treated with oral digoxin, that had more than one digoxin measurement were included. Serum digoxin measurements performed before achievement of pharmacological steady state were considered as inappropriate. The chi-square and chi-square for trend tests were used to analyse the relationship between inappropriate measurements and age, gender, diagnosis, inpatient service, serum digoxin, potassium and creatinine concentrations.

We evaluated 2065 hospital admissions for 1621 patients and 11,407 digoxin measurements. The time between consecutive measurements was 1.9 ± 2.4 days and 97% of all measurements were classified as inappropriate. There was no releationship between patient age, gender, serum creatinine concentration and inappropriate measurement. As opposed to expected, inappropriate digoxin measurement was higher when potassium concentrations were within the normal range (P = 0.025). Share of inappropriate determinations of digoxin was higher when concentrations > 2.6 nmol/L were recorded (P < 0.05). These measurements were requested most often in coronary care unit and cardiology department.

In our study, inappropriate serum digoxin measurement was found to be very high although only one of the appropriateness criteria was evaluated. The findings reveal the need for some strategies to prevent inappropriate measurements and reduce costs.