Overview
ISO 21474-3:2024 - In vitro diagnostic medical devices - Multiplex molecular testing for nucleic acids - Part 3: Interpretation and reports sets out general requirements and guidance for the interpretation and reporting of multiplex molecular tests that detect two or more nucleic acid targets. Applicable to both commercial IVDs and laboratory-developed tests (LDTs), the standard covers qualitative and quantitative assays for human and microbial nucleic acids from clinical specimens. It excludes metagenomic massive parallel sequencing (MPS) but applies to multiplex methods such as 16S sequencing.
Key topics and requirements
- Fit‑for‑purpose interpretation: Interpretation methods must be validated and documented; results should be reviewed by trained molecular diagnostic professionals.
- Documentation and SOPs: Laboratories must maintain documented procedures for interpretation, reporting, algorithms, software, and databases used in bioinformatics analysis.
- Bioinformatics governance: Record and version-control all algorithms, software components and databases used for analysis; include procedures for monitoring and updating pipelines.
- Variant handling: Requirements for variant identification, annotation and evidence-based categorization (classification, scoring, indexing); ongoing re-evaluation of clinical significance is expected.
- Multivariable and algorithmic tests: Guidance for assays that combine multiple biomarkers (e.g., miRNA panels) into risk scores or classifiers, including cut-off use, algorithm validity monitoring, and reporting of composite results rather than individual analyte readings when appropriate.
- Reporting content: Specifies reporting elements and test report content, including how to present detected variants, secondary findings, and method descriptions to support clinical decision-making.
- Risk mitigation: Procedures to minimize cognitive bias, use of automated interpretation where appropriate, and consideration of prevalence effects on PPV/NPV.
Practical applications and who uses it
ISO 21474-3:2024 is designed for practical use across the molecular diagnostics ecosystem:
- Medical laboratories performing multiplex PCR, microarray, targeted sequencing, or 16S assays
- IVD manufacturers and assay developers creating multiplex panels and interpretation software
- Clinical laboratory directors and molecular pathologists standardizing report content and variant classification
- Regulatory authorities and quality managers assessing conformity with reporting and bioinformatics requirements
- Biobanks and research organizations producing clinically actionable multiplex results
Adopting this standard helps ensure consistent, traceable, and clinically meaningful reports from multiplex molecular testing, improving patient care and interoperability across laboratories.
Related standards
- ISO 15189 - Medical laboratories - Requirements for quality and competence
- ISO 21474-1 - Terminology and nucleic acid quality evaluation for multiplex tests
- ISO 20397-2 - Guidance for MPS (where applicable)
- ISO/IEC/IEEE 90003 - Software quality guidance for interpretation tools
Keywords: ISO 21474-3:2024, multiplex molecular testing, in vitro diagnostic (IVD), interpretation and reports, bioinformatics, variant annotation, multivariable molecular tests.