Digoxin level and clinical manifestations as determinants in the diagnosisof digoxin toxicity

The aim of this study was to determine the relative importance of different risk factors in the diagnosis of digitalis toxicity. The authors recruited inpatients for whom serum digoxin level was requested and prospectively fo llowed them fbr a week to ascertain if they showed digitalis toxicity. The predictive value of different factors for the assessment of digoxin toxicit y was analyzed by multiple logistic regression. Forty-one toxic and 58 nont oxic patients were included. In the univariant analysis, intoxicated patien ts were older, most were women, and they had worse renal function and highe r digoxin level; but there were no differences in serum electrolytes or oth er risk factors. In the multivariant analysis, digoxin level was the only i ndependent factor related to digitalis toxicity. A different risk of toxici ty for each clinical manifestation was found for a certain digoxin level.:P atients with signs of automaticity in the electrocardiogram had a higher li kelihood of being intoxicated than patients with gastrointestinal symptoms, atrioventricular block, or bradycardia. Therefore, in the population evalu ated in this study, digoxin level is the key independent factor in digoxin intoxication, although the probability of being intoxicated is also a funct ion of the type of clinical manifestations. A graphic approximation of this probability based on these two factors is presented.