The impact of preanalytical variability in clinical trials: are we underestimating the issue?

The essential contribution that the preanalytical phase plays to the reliability of the total testing process and the quality of diagnostic information is now clear to most laboratory professionals (1). The recent release of the 2015 STARD guidelines has further contributed to catalyze the attention on this topic (2-4), also emphasizing the importance of preanalytical activities in the quality of diagnostic studies (5). Nevertheless, the familiarity of many scientists and clinicians with extra-analytical issues remains vague, at best. The role and active involvement of experts or national and international organizations of laboratory medicine has propelled the generation of a consistent literature, culminating in robust and sizeable recommendations aimed to define best practice criteria for accurate and appropriate handling of biological specimens before analysis. Such a huge scientific effort has been paralleled by a number of technological advances in the materials used for drawing blood and in the procedures for collection, transport, centrifugation, separation and storage of biological materials. The high degree of complexity and heterogeneity in the preanalytical phase is mainly attributable to the analysis of different biological fluids (e.g., whole blood, serum, plasma, urine), less frequently used biological materials such as saliva, hairs, stools, and even of specimens necessitating special preparations (i.e., nucleic acids, supernatants or cell cultures). Additional sources of vulnerability emerge from the use of different procedures and materials for collection of biological specimens (1).