Evaluation of two prediction models for digoxin dosing.

The relationship between the digoxin elimination parameter (A%) and creatinine clearance (CLCr) was determined, from blood level data of 160 hospital patients receiving digoxin tablets. The linear regression equation obtained, which varied only slightly from that reported by Jelliffee previously, was used to predict serum digoxin concentrations in 140 patients of four age groups (50-60, 60-70, 70-80 and 80-90 years). The predictions made were found to be less biased and more precise, irrespective of the age of the patients, than those produced using another predictive method known as Dobbs method. However, correlation coefficients of predicted versus measured serum digoxin concentrations for each method did not differ significantly and frequency distribution analyses of prediction errors gave poor results (up to 63% only). Therefore, neither method can be considered to be superior to the other nor can they be said to ensure accurate predictions of serum digoxin concentrations.