Pre- and post-analytical proficiency testing

Importance of the topic

Proficiency testing (PT) and external quality assessment (EQA) schemes are established tools for evaluating analytical performance, but conventional schemes frequently evaluate only the measurement step. Pre- and post-analytical processes — including sampling, sample handling, result interpretation, uncertainty evaluation, reporting, and communication with clients or regulators — contribute meaningfully to overall laboratory quality and decision-making. Extending PT/EQA to include these stages reveals weaknesses not visible in measurement-focused schemes, supports harmonisation of practice, and aligns with accreditation standards that call for assessment of the entire testing process.

Aims and study overview

The document outlines the rationale for incorporating pre- and post-analytical elements into PT/EQA schemes and provides practical examples to inspire providers. Its goals are to demonstrate how such schemes can detect deviations from guidelines, variability in sample handling or interpretation, and gaps in communication and decision-making; and to encourage providers to develop or expand schemes that evaluate the full analytical workflow.

Methodology and approach

Pre- and post-analytical PT/EQA schemes typically use scenario-based and simulated materials rather than solely homogenous analytical samples. Key methodological features include:

• Provision of contextual information (e.g., patient history, food consumption, legislative limits) together with a test sample or simulated dataset.
• Use of synthetic or real-world items where pre-analytical actions (sampling decisions, selection of tests, or selection of test clauses) are part of the exercise.
• Assessment by expert panels or providers who rank or comment on participant responses, including interpretative advice, reporting practices, and actions such as notifications to stakeholders.
• Feedback reports that compare participant performance, present model answers or recommendations, and identify typical errors or best practices.

Main results and discussion (illustrative examples)

The document presents four illustrative scheme types that show how pre- and post-analytical PT/EQA add value:

• Interpreting clinical chemistry information — participants receive analytical results plus clinical background and are evaluated on their interpretation and clinical advice; expert scoring highlights consistency and divergence in interpretive practice.
• Sampling requests in microbiology — food-poisoning scenarios require participants to choose organisms and tests to perform, report methods and results, and decide on stakeholder notifications; this reveals variability in sampling strategy and public-health decisions.
• Toy testing — participants assess the safety of a distributed toy sample against a standards document (EN 71), selecting applicable clauses and tests; this exposes differences in clause interpretation and test selection decisions.
• Monitoring drinking water quality — participants test synthetic water near regulatory limits and must report results, uncertainties, and pass/fail decisions; providers use the exercise to review laboratory decision rules and to inform regulators where appropriate.

These scenarios show that including pre- and post-analytical tasks can uncover non-analytical sources of error (e.g., inappropriate test selection, inconsistent interpretation, or reporting deficiencies) that standard PT samples would not detect. The schemes also provide a basis for targeted education, guideline refinement, and regulatory dialogue.

Benefits and practical applications

Pre- and post-analytical PT/EQA schemes deliver several practical benefits:

• Improved harmonisation of practice across laboratories by identifying divergences in sampling, interpretation, and reporting.
• Enhanced training value because feedback covers decision-making and workflow steps, not only measurement accuracy.
• Support for accreditation and standardisation efforts by aligning with requirements that call for evaluation of the entire process (for example ISO 15189 in medical laboratories).
• Opportunities to inform regulators and stakeholders about common laboratory practices and systemic issues, enabling policy or guidance updates.
• Better preparedness for real-world incidents (e.g., outbreaks or consumer-product safety events) through scenario-driven exercises.

Future trends and applications

Potential directions for the development and broader adoption of pre- and post-analytical PT/EQA include:

• Digital and virtual proficiency exercises that simulate patient records, laboratory information systems, or regulatory workflows to test interpretation and reporting without physical samples.
• Integration of whole-process evaluation into accreditation programmes and routine EQA offerings across sectors beyond clinical laboratories — food safety, environmental monitoring, and consumer-product testing.
• Use of standardized scenario libraries to enable comparability across providers and jurisdictions and to accelerate harmonisation of best practices.
• Advanced analytics on PT/EQA results (trend analysis, root-cause mapping) to identify common error patterns and target corrective actions.
• Greater stakeholder involvement (clinicians, public-health authorities, regulators) in scheme design and feedback loops to ensure practical relevance of exercises and to support policy changes.

Conclusion

Pre- and post-analytical PT/EQA schemes extend quality assessment beyond instrument performance to the entire testing process, revealing decision-making and procedural gaps that affect patient safety, public health, and regulatory compliance. Scenario-based designs and expert feedback increase educational value and support harmonisation, guideline improvement, and stronger links between laboratories and regulators. Providers are encouraged to expand such schemes to cover a wider range of pre- and post-analytical activities and to leverage digital tools and analytics for scalable implementation.

Reference

Produced by the Eurachem Proficiency Testing Working Group, Second English edition, July 2022. Eurachem publication on pre- and post-analytical proficiency testing and external quality assessment.