The importance of having a flexible scope ISO 15189 accreditation and quality specifications based on biological variation – the case of validation of the biochemistry analyzer Dimension Vista

Introduction: Technological innovation requires the laboratories to ensure that modifi cations or incorporations of new techniques do not al ter the quality of their results. In an ISO 15189 accredited laboratory, fl exible scope accreditation facilitates the inclusion of thes e changes prior to accreditation body evaluation. A strategy to perform the validation of a biochemistry analyzer in an accredited laboratory having a fl ex ible scope is shown. Materials and methods: A validation procedure including the evaluation of imprecision and bias of two Dimension Vista analysers 1500 was conducted. Comparability of patient results between one of them and the lately replaced Dimension RxL Max was evaluated. All studies followed the respective Clinical and Laboratory Standards Institute (CLSI) protocols. 30 chemistry assays were studied. Coeffi cients of variation, percent bias and total error were calculated for all tests and biological variation was considered as acceptance criteria. Quality control material and patient samples were used as test materials. Interchangeability of the results was established by processing forty patients’ samples in both devices. Results: 27 of the 30 studied parameters met allowable performance criteria. Sodium, chloride and magnesium did not fulfi l acceptance criteria. Evidence of interchangeability of patient results was obtained for all parameters except magnesium, NT-proBNP, cTroponin I and C-reactive protein.