An interlaboratory study of the determination of digoxin by immunoassay.

We conducted a voluntary survey of laboratories and manufacturers to assess the current quality of analytical assays for serum digoxin. More than 300 clinical laboratories and 18 manufacturers responded, giving data on methods, instruments, computational procedures, and results for five survey samples. We sorted the analytical data to provide statistical information on the grand mean values separately for manufacturers and clinical laboratories, the frequency distribution of all reported values, and the mean values by method of interpolation and algorithms used for linear transformation. There was no statistical difference (alpha = 0.05) between the means for each specimen as determined by the kit manufacturers as a group and the clinical laboratories as a group.