Intervalli di riferimento comuni? Utili? Possibili? Necessari?

Abstract

The theory of the reference interval has been well-defined by authoritative professional institutions but its practical application in most clinical laboratories is far from optimal. Laboratories often use different reference intervals without any valid reason, such as variations in analytical methodology or the population served. The adoption of common reference intervals has become a matter of importance because: (1) several common decision points which are not determined or validated in individual laboratories, e.g. glucose and lipid measurements, have already been widely accepted; (2) common reference intervals have been developed in Scandinavia by an international clinical chemistry organisation (Nordic Reference Interval Project, NORIP) and are being developed in Oceania; (3) the approach has been discussed favourably at international meetings; and (4) assay standardisation has substantially advanced (e.g. in the European Union). In 1998 the NORIP programme was started with the participation of 102 Nordic clinical biochemistry laboratories which collected blood samples from at least 25 healthy reference individuals evenly distributed for gender and age, and determined 25 of the most commonly requested serum/plasma components for each reference individual. Analytical and methodological data and data describing the reference individuals were submitted to a central database for evaluation and calculation of reference intervals intended for common use in the Nordic countries. Today, common reference intervals are used by almost 100% of laboratories for some analytes (e.g. iron, bilirubin, urate, magnesium). In 2005/06 the UK Department of Health set up a national Action Learning Programme as a key part of its Modernising Pathology Programme to enable people working in NHS pathology services to tackle issues and problems they identify locally as a priority for action. The Department funded six action learning sets to work on priority areas in pathology: workforce, standardisation, networks, primary care and protocol-guided investigations. The first phase was a success and was followed by a second phase with 16 topics. Work on the learning set for harmonise of reference intervals was carried out in the West Midlands. The set took a pragmatic approach to harmonising the variations between laboratories. Different practices were identified and were examined to see whether reasons for the differences were technical, scientific or clinical (e.g. differences in equipment and reagents or in the population served). The variations at the top and bottom were then considered, and a proposal based on consensus was developed. From 2007, the Pathology Harmony Initiative started to look at the harmonisation within the clinical laboratory. Several areas were identified where it was felt that there was potential for harmonisation. Several topics (e.g. units of measurement, reference intervals, test name harmonisation) have been investigated. All these experiences demonstrate that harmonisation of the reference intervals for several analytes should at last also be considered in Italy.