Regresar

Application of the analytical quality specifications to the calculation of the allowable limits of error in Programs of External Quality Assessment for sperm concentration

Abstract:

Introduction: External quality assessment is an essential activity of the andrology laboratory. To evaluate the effectiveness of the laboratories participating in the Programme of External Quality Monitoring (PSEC) allowable limits of error are used, and the result of a laboratory is considered acceptable if it is within these limits. Currently allowable error limits depend to a large extent on the criteria of the organizers of the PSEC. Our goal is to compare the different criteria described in ISO 13 528:2005 for the calculation of the allowable limits of error discussed in the PSEC for sperm concentration, so that they can be used by all. Material and methods: The data analysed in this study are the mean values and standard deviation (SD) obtained on independent control samples from two PSEC. Four different strategies for calculating the allowable limits of error according to ISO 13 528:2005 were set: 1) based on the results of participating laboratories, 2) based on the results of expert laboratories, 3) using quality specifications based on biological variability, state of the art and opinion of clinicians, and 4) using the quality specifications and adjusting for the uncertainty of the assigned value. Results: Very large allowable limits of error were obtained with strategies 1 and 2, whereas strategy 3, based only on quality specifications, gave very narrow limits.. However, with strategy 4 we obtained values of intermediate acceptance intervals compared with the other strategies. There were no differences in the allowable limits of error in strategies 3 and 4 by varying the model for the calculation of analytical quality specifications. Discussion: PSEC sperm concentration should use a strategy adjusted to the uncertainty of the value assigned to establish the allowable limits of error, since the acceptance intervals obtained are clinically useful, so that the values contained in them lead to clinically similar decisions. For expert laboratories to adequately define them is more important than the model chosen to estimate analytical quality specifications in a sperm concentrationós PSEC. © 2011 AEBM, AEFA y SEQC.