The impact of age on risk of adverse drug reactions to digoxin. For The Gruppo Italiano di Farmacovigilanza nell' Anziano

To assess the association of age and other potential risk factors with digoxin toxicity, adverse drug reactions to digoxin (ADRDIG) were studied in all patients (n = 1338) on digoxin therapy consecutively admitted to 41 clinical wards throughout Italy during 4 months in 1988. At the time of admission, 28 patients (2.1%) had evidence of ADRDIG. In multivariate logistic regression analysis, significant associations with ADRDIG were found for age > or = 80 years compared to age 65-79 years (OR = 2.75, 95% CI = 1.17-6.45), daily digoxin dosage of > or = 0.25 mg (OR = 2.51, 95% CI = 1.16-5.47), serum creatinine > or = 120 mumol/L (OR = 3.75, 95% CI = 1.69-8.32), and for treatment with amiodarone, propafenone, quinidine or verapamil (OR = 2.60, 95% CI = 1.07-6.30). Those aged < 65 years had a similar risk of digoxin toxicity as those aged 65-79 years (OR = 1.07, 95% CI = 0.28-4.12). Adverse drug reactions to digoxin were found in 1 in 50 patients hospitalized on digoxin therapy. Patients aged 65-79 years were not at increased risk for digoxin toxicity compared to younger patients, while advanced age (> or = 80 years) was an independent risk factor for this outcome.