Another suggestion for measuring predictive performance for aminoglycoside therapy

The correlation coefficient between the predicted and measured values (r), the mean error (M.E.) or mean weighted error (M.W.E.) and the mean squared error (M.S.E.) or mean weighted squared error (M.W.S.E.) are generally used to evaluate the performance of prediction methods of serum drug levels. It has been shown that peak concentration value correlates with the therapeutic response to aminoglycoside antibiotics and trough serum level correlates with aminoglycoside toxicity. r, M.E. or M.W.E., and M.S.E. or M.W.S.E. do not permit one to know the prediction quality of peak and trough serum levels. We suggest adding an evaluation criterion the accuracy which consists in counting, for a given prediction method and a given patient group, the percentage of measured peak (%PA) and trough (%TA) levels that belong to an interval centred on the predicted concentrations (PC>.