IVDR Rule 4: Why Self-Testing Isn't Near-Patient Testing

IVDR's Annex VIII gives self-testing and near-patient testing the same rule number — Rule 4 — and that pairing causes more misclassification than almost any other rule in the set. The two intended uses are not variations on a theme. Rule 4(a) sets a default class for self-testing. Rule 4(b) sets none at all for near-patient testing; it sends the device back to whichever rule would govern it in a laboratory. Treat them as one rule with one answer, and the classification file is wrong before the rest of the technical documentation is even drafted.

One rule number, two different questions

Annex VIII's Rule 4 is really two rules sharing a label. Rule 4(a) covers devices intended for self-testing — use by a layperson, typically at home, without a healthcare professional present. Rule 4(b) covers near-patient testing — performed outside a traditional laboratory environment, but still by a healthcare professional or a trained operator, such as at the bedside, in a clinic, or at the point of care. The regulation groups them because both move testing away from a central lab. It does not treat them alike once you ask what class the device gets, and reading past that distinction is where a point-of-care diagnostics program's classification work usually goes wrong first.

Self-testing: a default, not a fixed answer

Devices intended for self-testing default to Class C under Rule 4(a). Current MDCG 2020-16 guidance lists specific, lower-risk categories as exceptions — pregnancy, fertility, and cholesterol self-tests among them — that classify as Class B instead. That exception list is narrow and named, not a general discount for anything marketed as low-risk, and manufacturers should confirm a candidate product actually appears on it rather than assuming it qualifies by analogy. The default runs the other direction too: Rule 4(a) is not a ceiling. A self-test for an analyte governed by a higher-risk rule elsewhere in Annex VIII — an HIV self-test is the standard example — keeps that higher class. Making a test available to a layperson does not pull a high-risk analyte down to Class C.

• Default: Class C. Applies to self-testing devices unless a listed exception or a higher-risk rule says otherwise.
• Named exceptions: Class B. MDCG 2020-16 lists specific low-risk self-test categories — including pregnancy, fertility, and cholesterol tests — that step down from the Rule 4(a) default.
• No ceiling for higher-risk analytes. A self-test is not automatically capped at Class C; where another rule assigns a higher class to the analyte itself, that higher class controls.
• The IFU is the evidence. Whether a device is "intended for self-testing" is decided by its stated intended purpose and labeling, not by whether a layperson could physically operate it.

Near-patient testing was never supposed to be a shortcut to a lower class. Rule 4(b) exists precisely so that moving a test to the bedside doesn't quietly change the answer. Why Rule 4(b) has no default of its own

Near-patient testing: classified in its own right

Rule 4(b) works differently, and the difference is easy to miss because it reads like a classification rule without actually functioning as one. It does not set a default class for near-patient testing devices. It instructs manufacturers to classify the device "in its own right" — meaning by whichever Annex VIII rule would apply to the same intended purpose performed in a laboratory. A near-patient test for an analyte that would classify as Class B in a lab stays Class B at the bedside. A near-patient test for an analyte that would classify as Class C or D in a lab does not get a point-of-care discount. The setting changes where the test happens. It does not change which rule decides the class, and a classification file that cites "Rule 4(b): near-patient" as if that settled the question has skipped the actual analysis a companion diagnostics or point-of-care program needs on file.

A real example makes the mechanics concrete. Current MDCG 2020-16 guidance reclassified layperson self-use SARS-CoV-2 antigen tests from Class D down to Class C under Rule 4(a), reflecting the analyte's now-lower public-health risk profile. Professional-use SARS-CoV-2 tests — including near-patient, point-of-care use by a trained operator — landed at Class B, governed by the general rule that otherwise applies to that kind of IVD, not by Rule 4(b) assigning them anything directly. Same virus, same underlying analyte, two different Rule 4 branches, two different outcomes, and neither number came from Rule 4 handing out a class by default.

None of this is exotic once the two branches are kept separate. It is a bounded piece of work: fix the intended-user statement in the IFU, check the self-test exception list before assuming Class C, run the underlying-rule analysis for any near-patient use case, and keep the rationale for both on file. Manufacturers who treat Rule 4 as a single self-test rule tend to discover the near-patient branch exists only when a Notified Body asks why the classification file never addressed it — a question that is considerably cheaper to answer before submission than during review of a broader IVD regulatory strategy.