Original scientific paper

https://doi.org/10.11613/BM.2018.010705

Missed detection of significant positive and negative shifts in gentamicin assay: implications for routine laboratory quality practices

Gus Koerbin ; New South Wales Health Pathology, Chatswood, NSW 2067, Australia; Department of Biomedical Science, University of Canberra, Canberra, Australia
Jiakai Liu ; Department of Industrial and Systems Engineering, National University of Singapore, Singapore
Alex Eigenstetter ; New South Wales Health Pathology, Chatswood, NSW 2067, Australia
Chin Hon Tan ; Department of Industrial and Systems Engineering, National University of Singapore, Singapore
Tony Badrick ; Faculty of Health Sciences and Medicine, Bond University, Queensland, Australia
Tze Ping Loh ; Department of Laboratory Medicine, National University Hospital, Singapore; Biomedical Institute for Global Health Research and Technology, National University of Singapore, Singapore

Abstract

Introduction: A product recall was issued for the Roche/Hitachi Cobas Gentamicin II assays on 25th May 2016 in Australia, after a 15 - 20% positive
analytical shift was discovered. Laboratories were advised to employ the Thermo Fisher Gentamicin assay as an alternative. Following the reintroduction
of the revised assay on 12th September 2016, a second reagent recall was made on 20th March 2017 after the discovery of a 20% negative
analytical shift due to erroneous instrument adjustment factor.
Materials and methods: The practices of an index laboratory were examined to determine how the analytical shifts evaded detection by routine
internal quality control (IQC) and external quality assurance (EQA) systems. The ability of the patient result-based approaches, including moving
average (MovAvg) and moving sum of outliers (MovSO) approaches in detecting these shifts were examined.
Results: Internal quality control data of the index laboratory were acceptable prior to the product recall. The practice of adjusting IQC target
following a change in assay method resulted in the missed negative shift when the revised Roche assay was reintroduced. While the EQA data of the
Roche subgroup showed clear negative bias relative to other laboratory methods, the results were considered as possible ‘matrix effect’. The MovAvg
method detected the positive shift before the product recall. The MovSO did not detect the negative shift in the index laboratory but did so in
another laboratory 5 days before the second product recall.
Conclusions: There are gaps in current laboratory quality practices that leave room for analytical errors to evade detection.

Keywords

error; moving average; bias; quality control; quality assurance

Hrčak ID:

189595

URI

https://hrcak.srce.hr/189595

Publication date:

15.2.2018.

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