Mortality findings raise more concerns over digoxin's use

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Atrial fibrillation patients taking digoxin may have a 71 percent higher risk of dying, according to a study published online Nov. 20 in Circulation: Arrythmia and Electrophysiology.

In a retrospective look at real-world clinical cases, James V. Freeman, MD, PhD, MS, of Yale University School of Medicine in New Haven, Conn., and colleagues found that patients with arrhythmia taking digoxin for the first time had increased risk for death and hospitalization compared with patients on other treatments. This was in accordance with previous studies on the subject.

Using 2006 to 2009 data from Kaiser Permanente Northern California and Southern California systems, Freeman et al compared outcomes between matched cohorts of atrial fibrillation patients on digoxin for the first time and those receiving other treatments.

Rate of death for patients on digoxin was 8.3 per 100 patient years, compared with 4.9 per 100 patient years in nondigoxin users. Unadjusted, this translated to a 71 percent higher risk of death in patients taking digoxin. Hospitalization rates were 60.1 vs. 37.2 per person years for patients who were taking digoxin or not, respectively. Before adjustment, patients taking digoxin were at a 63 percent higher risk for repeat or lengthy hospitalization.

When adjusting for comodbidities, digoxin use was still associated with a 62 percent higher risk of death and 45 percent higher risk of hospitalization than nonuse.

They also found that serum digoxin concentration was never measured in 31 percent of patients, measured only once in 27 percent of patients and measured twice in 17 percent of patients. Only a quarter of patients had their serum concentrations checked three or more times during follow-up.

Freeman et al noted that they were not able to assess causes of death in the cohort. The rate of serum concentration measurement was concerning as it indicates “routine surveillance of digoxin levels is not commonly performed in community practice.”

Digoxin, they recommended, should be used with caution in managing atrial fibrillation as other rate control options exist.