RCPAQAP First Combined Measurement and Reference Interval Survey.

Reference intervals are commonly considered to allow for between-laboratory bias. The RCPAQAP Liquid Serum Chemistry Program has collected data on laboratory measurements as well as reference intervals. This allows assessment of the between-laboratory variation in results, reference intervals and the information transmitted by the combination of these factors. For the majority of common chemistry analytes, the between-laboratory variation in reference intervals is greater than the variation in results. Additionally the reference interval variation is generally not related to bias between the results. Use of common reference intervals, either as an average of the current intervals in use, or the intervals proposed by the AACB Harmonisation Group, improved the variation seen in the information produced by different laboratories.