engleski

Biological Variation: A Still Evolving Facet of Laboratory Medicine

Numerical data on the components of random biological variation (BV) have been generated for over 40 years. These have been used for a variety of purposes in laboratory medicine, including setting analytical quality specifications, assessing the significance of the difference seen in serial results from an individual and investigating the utility of conventional population-based reference values.1 The generation of such data is not easy.2 However, applications are facilitated through the availability of databases which give single figures for the components of BV, namely, within-subject (CVI) and between-subject (CVG). Recently, Simundic et al published a proposal for the standardised use of symbols and terms to define the components of BV: recommended were CVI for within-subject biological variation, CVG for between-subject biological variation and CVA for analytical variation.10 For analytical variation, it was recommended that mode of derivation and type (such as reproducibility, reliability, or total) as well as the number of analyses, runs, and time period should always be provided. In addition, terms and calculation formulae were recommended for the reference change value (RCV) and the index of individuality (II).

biological variation ; terminology ; guidelines ; bias

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