How often to run quality control at the point of care: no single answer
Ask ten point-of-care testing teams how often they run quality control and you will get ten different answers. Some run a control every morning out of habit. Some run one only when a new box of cartridges arrives. Many follow whatever the device leaflet suggested on day one and have never revisited it.
The honest position, which most academic guidance buries under caveats, is this: there is no universal QC frequency that fits every analyte on every device in every clinic. That is not an excuse to do less. It is the starting point for doing it properly. The right frequency is the one that catches a problem before it reaches a patient result, weighed against the realistic risk of your specific test, your specific device and your specific workload. This guide turns that idea into a score you can apply on Monday morning.
Why “just run it daily” is only half right
A blanket daily rule is a reasonable floor, and we will come back to it, but on its own it does two things wrong. It over-tests low-risk, highly stable single-use tests, wasting controls and staff time. And it under-protects high-throughput analysers running critical analytes, where a single morning run can sit happily over hundreds of patient samples before the next check.
QC frequency is really a risk question. A 2022 study in Clinical Chemistry and Laboratory Medicine examined exactly this for primary-care settings and proposed a scoring approach rather than a fixed number. It weighted the clinical importance of the result, the behaviour of the instrument and the testing volume, then let that combined score drive how often internal QC should run. The principle travels well beyond primary care, and it is the backbone of the practical tool below.
The five factors that should set your frequency
Before scoring, get clear on what actually moves the dial.
1. Analyte criticality
How much harm follows a wrong result before anyone notices? A potassium or lactate result can change treatment within minutes, so the cost of an undetected drift is high. A screening marker with a confirmatory follow-up step carries less immediate risk. Markers such as CRP sit in the middle: they guide decisions but rarely act alone.
2. Device type and stability
A single-use cassette with built-in process controls behaves very differently from a bench analyser holding open liquid reagents. The cassette tends to fail in obvious ways. The bench analyser can drift quietly as reagents age, lamps dim or temperatures wander, and that is precisely the kind of slow change QC is meant to catch.
3. Ease of use and operator factors
Count the steps and the hands. A guided, near-foolproof device used by two trained staff is lower risk than a multi-step manual method shared across a rota of occasional users. More manual steps and more operators mean more chances for a result to go wrong between checks.
4. Daily throughput
A device running a handful of tests a week needs a different rhythm from one running steadily all day. The more patient results that pass between two QC runs, the more results are exposed if something has slipped.
5. EQA track record
Your external quality assessment (EQA) history is the reality check. Consistent good performance earns confidence to stay at your chosen level. Recent flags, a new method or a freshly installed device argue for tighter internal QC until you have proof of stability.
A risk score you can apply on Monday
Score each factor from 0 to 2, then add them up for a total out of 10.
| Factor | Score 0 | Score 1 | Score 2 | |—|—|—|—| | Analyte criticality | Low impact, confirmatory step follows | Moderate, supports a decision | High, drives immediate treatment | | Device type and stability | Single-use cassette with process controls | Small, stable bench analyser | Multi-reagent analyser, open liquid reagents | | Ease of use and operator factors | Guided, few steps, guided lockouts | Some manual steps | Multi-step manual prep, many or occasional users | | Daily throughput | A few tests a week | Moderate daily use | High volume through the day | | EQA track record | Consistently good | Occasional flags | Recent failure, new device or new method |
A test that scores 9, say a manually prepared critical analyte on a busy multi-reagent analyser with a recent EQA flag, clearly needs more frequent QC than a stable single-use screening test that scores 2. The score does not replace judgement. It makes the judgement visible and defensible, which is exactly what an assessor wants to see.
The once-a-day floor: what ISO 15189:2022 expects
ISO 15189:2022, the international standard for the quality and competence of medical laboratories and the one most POCT services are judged against, does not hand you a number for every test. Described in plain terms rather than quoted, it asks you to run QC at a frequency matched to the risk and stability of each examination, and to set out that frequency in your own documented procedures.
In practice, for quantitative analysers, running internal QC on each day of patient testing is the widely accepted floor that accreditation bodies expect to see, with more frequent runs where the risk score is higher. Single-use devices that carry internal or electronic controls may follow a reduced external QC schedule, but they still need periodic liquid QC and a control run at every new lot and shipment. Read the official standard text before you finalise your policy, rather than relying on any summary.
Your frequency decision matrix
Map your total score to a starting cadence, then adjust for local realities.
| Total score | Risk band | Suggested internal QC cadence | |—|—|—| | 0 to 3 | Lower | One QC run on each day of patient testing for quantitative analysers, plus a run at every new lot and shipment. For single-use devices with internal controls, a documented reduced schedule plus periodic liquid QC. | | 4 to 6 | Moderate | At least one run on each testing day, both QC levels where the method offers them. Add a second run on long days or when several operators are involved. | | 7 to 10 | Higher | Each testing day plus per-shift or per-batch checks for the critical analytes, two QC levels, and tighter result-review rules. |
The daily floor still applies even at low scores for quantitative methods. The score tells you how much further above that floor to go, not whether you can drop below it.
Why good QC policies still get missed, and how to fix it
Even a well-judged schedule fails if it lives in a folder. The common failure modes are familiar: a busy morning where QC is skipped “just this once”, a new starter who does not know the rota, a control that expired unnoticed, a second device that nobody was assigned to. Across several sites and a mix of devices, tracking all of this on paper is where policies quietly fall apart, and the gap usually only surfaces during an audit.
This is where digital scheduling earns its place. A system that knows each device’s required cadence can prompt the right person at the right time, flag overdue runs before patient testing starts, and keep a clean record of what ran, when, and with what outcome. Where a result matters most, testing can be held until QC has passed. POCTIFY builds this kind of QC scheduling and reminder layer around point-of-care services, working with the devices and systems you already use, so the schedule you designed on paper is the schedule that actually runs each day.
Bringing it together
Set your floor at one QC run on each day of patient testing for quantitative analysers. Then score each test on the five factors and move up from there. Re-score whenever something changes: a new device, a new group of operators, a shift in volume or an EQA flag. The aim is not the most QC, it is the right QC, supported by a clear rationale you can put in front of an assessor.
If you would like a second pair of eyes on your QC schedule, or help turning a risk score into an automated routine across your sites, Talk to POCTIFY. We tailor digital point-of-care support to how your clinic actually works.
This article is for educational and operational purposes only and is not medical advice. It does not guide the diagnosis, interpretation or treatment of any individual patient. Always consult the official text of any standard, and your manufacturer’s instructions for use, when setting your own QC policy.
Frequently asked questions
Is running QC once a day enough for point-of-care testing?
For many quantitative analysers, one QC run on each day of patient testing is a sensible floor and is what most accreditation assessors expect to see. It is not always enough. High-throughput devices running critical analytes such as potassium or blood gases often need per-shift or per-batch checks, because many patient results can pass between a single morning run and the next. Score the test on clinical risk, device stability, operator factors, volume and EQA history to decide whether to go above the daily floor.
Do single-use cassette tests still need external quality control?
Yes. Built-in process or electronic controls confirm that the device read a strip, not that the result is accurate against a known value. A risk-based schedule for single-use devices usually combines those internal checks with periodic liquid (external) QC and a control run at every new lot and shipment. Document the reduced schedule and the reasoning behind it so it stands up to review.
What does ISO 15189:2022 say about QC frequency?
In broad terms, ISO 15189:2022 asks laboratories and POCT services to run quality control at a frequency matched to the risk and stability of each examination, and to define that frequency in their own documented procedures rather than rely on a single fixed rule. It does not print a number for each test. Running QC on each day of patient testing is the widely accepted floor for quantitative methods. Consult the official standard for the exact wording before writing policy.
How does EQA affect how often I run internal QC?
External quality assessment (EQA) tells you whether your results agree with peers and target values over time. A strong EQA record supports keeping internal QC at your risk-based level. Recent EQA failures, a new method or a newly installed device are good reasons to increase internal QC frequency until you have rebuilt confidence in the result.
Should I run one or two QC levels?
Where a method offers more than one control level, running two (for example a normal and an abnormal) checks performance across the measuring range rather than at a single point. Higher-risk and higher-volume tests benefit most from two levels on each testing day. Lower-risk, very stable tests may justify a single level with periodic two-level checks, provided you record the rationale.
