Performance evaluation and planning for patient-based quality control procedures

In a recent publication, the effect of the length of time between the routi ne testing of quality-control (QC) samples on QC performance was studied us ing a newly proposed performance measure: the average number of patient sam ples that contain unacceptable analytic error due to an out-of-control erro r condition (ANP(TE)). We show that ANP(TE) also perfectly suits the evalua tion of patient-based QC procedures. We used ANP(TE) to study the effect of the number of patients results averaged and the width of the truncation li mits on an average of normals QC procedure. Estimates of ANP(TE) were obtai ned by suing computer simulations that use actual patient result distributi ons. Based on ANP(TE), the conclusions about the effects of truncation limi ts and number of patient results averaged on the performance of an average of normals QC procedure are substantially different from those described by others using the probability of error detection to characterize QC perform ance.