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Daly, Susan (2024) Novel approaches to quality control and harmonisation of analysers within a veterinary laboratory system. PhD thesis, University of Nottingham.

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Abstract

The purpose of the research project was to develop a novel laboratory quality system to harmonise the five separate laboratories operating a commercial diagnostic service. Methods for initial and ongoing maintenance of harmonisation of haematology analysers within the laboratories were developed and implemented.

This project involves novel studies, as there are no relevant publications in the veterinary literature on these topics. The literature review presented in chapter 1 provides an overview of harmonisation followed by sections that cover the methods, tools and approaches used to assess the performance of the analytical network and to implement innovative quality control (QC) methods for veterinary haematology analysers.

Chapter 2 provides the first report of a comparison of performance evaluations for a network of six Sysmex analysers. A three-step process was used to evaluate and optimise performance to achieve harmonisation using quality parameters such as biologic variation for bias and CV, sigma metrics and total error as recommended by American Society of Veterinary Clinical Pathology (ASVCP).

Chapter 3 describes a quality control validation approach to maintain the harmonisation status and support the transition to harmonisation to ensure suitable clinical interpretation across the laboratory network. The results demonstrated that using a QC-rule based on the performance of individual analysers rather than manufacturers’ acceptable limits improved the probability of error detection (Ped) and reduced the probability of false rejection (Pfr) for veterinary haematology analysers. In conjunction with a high sigma strategy, achievement of biologic variation-based goals and TEa as recommended by ASVCP or expert opinion were used to establish acceptable performance for harmonisation across the analytical network.

Chapter 4 presents a first report of validating repeat patient testing-quality control (RPT-QC) using retained patient specimens for a network of haematology analysers as an alternative to commercial quality control material. Veterinary specific quality control material is not readily available which presents a difficult challenge for veterinary laboratories as a commutable matrix would be from animal origin. The repeat patient testing quality control (RPT-QC) could detect unstable analytical performance and RPT-QC limits were successfully generated using 40 data points rather than using 20 data points that was previously recommended. RPT-QC limits were required for each individual analyser and sigma metrics provided a useful performance tool to indicate suboptimal performance.

Chapter 5 outlines the process of implementation of RPT-QC, including an evaluation in parallel with the commercial quality control material to give confidence that RPT-QC can be used as practical alternative to commercial quality control material and that each individual analyser requires validation.



Chapter 6 outlines the design, evaluation and implementation of an internal laboratory comparative (ILC) testing program to maintain harmonisation by comparing the network analysers to the designated reference analyser. The ILC program used surplus canine samples with results across a range of clinical importance. Evaluation of the ILC results indicated that the ILC testing program could be used as an alternative to multiple subscriptions to an external quality assurance (EQA) program. This successful implementation offered a species-specific advantage and could determine whether performance issues were attributed to bias and/or imprecision and whether the interpretation of results was interchangeable between the network analyser and the reference analyser.

Chapter 7 outlines a pilot program for comparative testing offered to veterinary practices with in-clinic point of care testing (POCT) haematology analysers in comparison to the network reference haematology analyser. This study aimed to determine if the results of the POCT analysers could be harmonised with the reference analyser to ensure that results were interchangeable and clinically useful for diagnosis and monitoring, whether the results were generated by the POCT analyser or the reference analyser.

Chapter 8 is a discussion of the innovative approaches used in this study and reflections that may be useful for other veterinary laboratories desiring to achieve harmonisation for a network of analysers, wish to design their own comparative testing programs and/or provide comparative testing for clients with POCT analysers.

This chapter also describes the limitations and challenges associated with this research and possible future directions.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Freeman, Kathy Graham, Peter Kendall, Nigel
Keywords:	Veterinary laboratories; Quality control; Haematology analysers; Comparative testing; Laboratory comparative testing program
Subjects:	S Agriculture > SF Animal culture
Faculties/Schools:	UK Campuses > Faculty of Medicine and Health Sciences > School of Veterinary Medicine and Science
Item ID:	78313
Depositing User:	Daly, Susan
Date Deposited:	17 Jul 2024 04:40
Last Modified:	17 Jul 2024 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/78313

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