INCIDENCE OF DIGOXIN TOXICITY IN OUTPATIENTS

The incidence of digoxin toxicity among patients in hospitals has decl ined in recent years. To evaluate whether a similar decline has occurr ed in ambulatory care, we reviewed randomly selected medical records f or 183 outpatients receiving ongoing treatment with digoxin at 10 urba n and rural Department of Veterans Affairs medical Centers in the Rock y Mountain region. The prevalence of traditional risk factors for digo xin toxicity-elevated serum digoxin and serum creatinine levels, hypok alemia, and a new prescription of an interacting drug-was established from compsuterized laboratory and pharmacy records. Of the 183 patient s, 50 (27.3%) had one or more risk factors for digoxin toxicity: serum digoxin levels were elevated in 13.6% of patients in whom a level was obtained, with hypokalemia in 14.3%, elevated creatinine levels in 17 .9%, and possible drug interactions in 5.5% of patients over a 1-year period. Nevertheless, digoxin toxicity occurred in only 2 persons (1.1 % or 1.4 per 100 patient-years of treatment). We conclude that digoxin toxicity was rare in this group of outpatients, even in persons presu med to be at high risk because of metabolic abnormalities, increased d igoxin concentrations, or the use of interacting drugs. The low rate o f digoxin toxicity in outpatients parallels the decline in the inciden ce of toxicity observed in hospital-based studies.