Reliability of biological variation data available in an online database: need for improvement

Background: Biological variation (BV) data enable assessment of the significance of changes in serial measurements observed within a subject and are used to set analytical quality specifications. This data is available in a database held in Westgard website (http://www.westgard.com/biodatabase1.htm). Some limitations of this data, however, have been identified in recent published reviews. The aim of this paper is to show the reliability of the published BV data and to identify ongoing works to address some of its limitations. Methods: The BV data currently hosted on the Westgard website was examined. Distribution of measurands stratified by the number of cited references upon which the database entry is based and the distribution of papers stratified by publication year, are shown. Moreover, BV data available in literature for glycated hemoglobin, C-reactive protein, glycated albumin, alanine aminotransferase, aspartate aminotransferase and.-glutamyl transferase are evaluated. Results: The results obtained show that most BV data come just from a few papers or only one paper and that a lot of publications are dated, therefore this data is too obsolete to be used. Furthermore critical review of the BV database highlights a number of factors that might impact on the reliability of the BV data entries and translation into current practice. Conclusions: A number of issues clearly undermine the value of the current database. These issues are being considered by the European Federation of Clinical Chemistry and Laboratory Medicine, biological variation working group, in collaboration with a Spanish group responsible for the database updating.