External quality assessment is how a laboratory proves to someone outside its own walls that its results are right. Under ISO 15189:2024 it is no longer optional for any examination — including point-of-care testing. This page is about planning it: which programmes a laboratory needs, how often, and how to combine providers into a portfolio that covers every discipline.
Control samples of unknown value are analysed like patient samples, and the results are compared with reference values and with other laboratories using the same method. That comparison — EQA, or proficiency testing (PT) — finds what internal quality control is blind to.
A calibration bias shifts every result in the same direction. Internal QC drifts with it; an outside reference does not.
A patient who moves between institutions needs results that mean the same thing in both. Interlaboratory comparison is how that is shown.
Accreditation bodies read EQA performance as evidence that calibration, reagents and staff work together as intended.
Clause 7.3.7.3 makes participation in EQA or proficiency testing mandatory for every examination the laboratory performs. The 2024 revision (in force in Russia as GOST R ISO 15189-2024) adds six points a quality plan has to cover:
| 01 · Participation | EQA / PT for every type of examination |
|---|---|
| 02 · Alternatives | Another form of interlaboratory comparison where no programme exists |
| 03 · Analysis | Systematic review of results, including trend detection — not just pass/fail |
| 04 · Corrective action | Documented CAPA for every unacceptable result |
| 05 · Risk | Risk-based prioritisation of controls |
| 06 · POCT | Point-of-care devices inside the quality management system — new in 2024 |
Each discipline has its own failure modes, and the programmes are built around them. The frequencies below are per year and describe typical schemes, not a fixed offer.
Enzymes, substrates, lipids, electrolytes, HbA1c. Up to 70 % of all laboratory tests fall here — the area where an undetected error reaches the most patients.
CAP (CHEM, GH2, ISE) 3–4× · Randox RIQAS up to 24× · Bio-Rad EQAS 12× · INSTAND 2–4× · Labquality 4–6×
Without external control: a systematic haemoglobin bias misclassifies anaemia, wrong platelet counts distort haemostasis, a faulty differential misses blast cells.
CAP (HEME, HEME2) 3–4× · Randox RIQAS 12× · UK NEQAS 6× · INSTAND 4×
Pathogen identification and susceptibility testing (MIC, MRSA, ESBL, carbapenemases), mycology, blood cultures, serology. Antimicrobial resistance makes accuracy here a public-health question.
CAP · UK NEQAS · INSTAND (incl. MALDI-TOF) · Labquality · QCMD
The most method-dependent area: results for one analyte differ between platforms, so peer grouping by method and analyser is essential. An hs-cTnI error can mean a missed infarction.
CAP · Randox RIQAS Cardiac · Bio-Rad EQAS · UK NEQAS
Every stage can fail on its own — extraction, amplification, detection, sequencing, bioinformatics, interpretation — and needs its own check.
QCMD · CAP NGS · INSTAND · EMQN · GenQA
INR depends on the thromboplastin ISI, the instrument–reagent-lot calibration and the endpoint method. Peer grouping by instrument and reagent combination is mandatory.
CAP · Randox RIQAS · Bio-Rad EQAS · UK NEQAS · INSTAND
New in ISO 15189:2024: every POCT device and parameter needs EQA. Devices run by non-laboratory staff, often without LIS connection, are exactly where errors go unseen.
CAP · Randox RIQAS Blood Gas · Bio-Rad EQAS · INSTAND · Labquality
Up to 20 % discordance in HER2 status between laboratories without EQA — and HER2 decides whether targeted therapy is prescribed. NordiQC rates protocols from optimal to poor.
NordiQC · CAP · UK NEQAS
No single provider covers every discipline equally well. The practical answer is a core of broad programmes that carry the routine work, extended by specialists for the high-technology disciplines.
CAP (USA) — the broadest coverage and the route to CAP
accreditation.
Randox RIQAS (UK) — up to 24 distributions a year, online
peer comparison.
INSTAND e.V. (Germany) — the DACH standard, simple
logistics for the region.
QCMD — molecular diagnostics and viral loads.
EMQN — molecular genetics (BRCA, CFTR, AML).
NordiQC — immunohistochemistry.
UK NEQAS — specialised tests with deep expertise.
The EQA plan follows from the test menu, and the test menu follows from the equipment. That is why we plan them together: instruments from 68+ European manufacturers, the reagents they run on, and the EQA programmes that prove the combination works. KombiMED is the official CAP distributor for Central Asia and the Caucasus.
Providers, programmes and the full presentation in the buyer portal.
Six months of CAP PT are the entry ticket. The path from there.
The questionnaire that shows where your laboratory stands today.
