A device intended for use by lay persons at home must meet MDR Annex I §22, which adds obligations on top of the general usability requirements in §5. The practical test is simple: the 70-year-old first-time user in a poorly lit kitchen must be able to use the device safely, and the manufacturer must prove it in the usability engineering file under EN 62366-1:2015+A1:2020.

By Tibor Zechmeister and Felix Lenhard.

TL;DR

  • MDR Annex I §22 imposes specific obligations on devices intended for use by lay persons, including home use, self-monitoring, and self-treatment devices.
  • Annex I §22 requires that devices perform appropriately under realistic variation in the lay user's technique, training, and environment.
  • EN 62366-1:2015+A1:2020 is the harmonised standard used to demonstrate conformity with §22 and §5.
  • Engineers consistently misjudge what is intuitive. Tibor has seen devices the engineering team called "obvious" fail with first-time home users on the most basic steps.
  • The test of a home use device is not whether a developer can use it. The test is whether a 70-year-old who has never seen it before can use it safely on the first attempt, alone, in a kitchen with average lighting.

Why home use is different

There is a category of usability failure Tibor has seen often enough to treat as a pattern. A team of young engineers builds a device, uses it daily themselves, iterates on the UI with colleagues, and declares it intuitive. They ship formative evaluations with users drawn from their own network. Everything looks clean. Then a notified body pushes them to run summative validation with representative lay users, and the results are ugly.

One case involved a home diagnostic device. The engineers were confident it was usable. When the summative study recruited users representative of the real population, one early participant was a woman in her seventies who had never used a touchscreen of that style before. She did not know to swipe. She pressed the logo at the top, expecting it to be a home button. She held the device upside down because the on-screen text orientation was not obvious to her. She ran the sample well past the time window because the timer cue was a thin progress bar in light gray, which she could not see. The device was not safe for her.

That person is not a mistake in the recruitment. That person is the intended user. MDR Annex I §22 exists precisely because the regulator knows engineering teams consistently underestimate the gap between what is intuitive to them and what is intuitive to a representative lay user.

What MDR actually says

MDR Annex I §22, under General Safety and Performance Requirements, addresses "devices intended to be used by lay persons." It states that such devices shall be designed and manufactured in such a way that they perform appropriately for their intended purpose, taking into account the skills and knowledge of lay persons and the influence resulting from the variation that can be reasonably anticipated in the lay person's technique and environment. The information and instructions provided must be easily understood and applied by the intended lay user.

The requirement is not narrow. It covers three things. First, the device itself must be robust to variation in technique. A home blood glucose meter must produce correct results even when the user holds it at a slightly wrong angle, applies slightly too much or too little blood, or runs the test at 15 °C instead of 25 °C. Second, the labelling and instructions must be readable and followable by lay users, which ties back to Annex I §23. Third, the device must reduce to a minimum the risk of incorrect results and the risk of use error leading to harm.

Annex I §22 is not standalone. It sits on top of Annex I §5, which is the general usability and ergonomics obligation. Annex I §5(b) explicitly names "lay, professional, disabled or other users" as categories the manufacturer must consider. For home use devices, §22 then adds the lay-user-specific layer.

The harmonised standard that operationalises both §5 and §22 is EN 62366-1:2015+A1:2020. Clause 5.1 of EN 62366-1 requires a use specification. For a home use device, that use specification must honestly characterise the lay user population, including age distribution, sensory capabilities, cognitive load under stress, literacy level, digital literacy, the physical environment, and the training the user will or will not receive.

A worked example

Consider a Class IIa wearable cardiac monitor intended for home use by patients after a cardiac event. The team's initial use specification says "adults aged 40 to 80 who have been discharged from hospital." Tibor would send that back immediately. It is not specific enough.

The honest use specification names the following characteristics. A meaningful fraction of users will be over 70 and have never worn a continuous monitoring device before. A meaningful fraction will have reduced visual acuity, some with early macular degeneration. A meaningful fraction will have reduced manual dexterity from arthritis. A meaningful fraction will be under emotional stress from the recent cardiac event, which reduces cognitive bandwidth. Most will receive a ten-minute handover from a nurse at discharge and no further training. Some will set up the device alone at home.

From that use specification, the team derives hazardous use scenarios under EN 62366-1 clause 5.5. Examples: the user applies the electrode patch in the wrong location, reducing signal quality and missing an arrhythmia event. The user misreads a low-battery warning and stops wearing the device. The user cannot pair the device to the app because the pairing screen assumes familiarity with Bluetooth. Each scenario maps to a risk control in the risk file under EN ISO 14971:2019+A11:2021.

The team then runs a formative evaluation with 8 representative users, weighted toward the harder end of the population: users over 70, users with reduced dexterity, users who have never paired a Bluetooth device. They find three problems the engineering team never saw: a button label that reads "pair" confuses users who think it refers to the electrode pair; a haptic vibration that engineers felt clearly is imperceptible to users with reduced sensation in the chest wall; and the quick start card uses icons the users cannot decode. All three become design changes. All three get validated in summative.

That is a home use device that has earned its §22 evidence.

The Subtract to Ship playbook

Felix coaches startups through this gap often, and the most effective move is a ruthless subtraction of assumed user skill. The founder's instinct is to add features for power users. The Subtract to Ship move is to strip the device down to the minimum necessary workflow and make that workflow bulletproof for the weakest representative user.

Step one is to rewrite the use specification using the 70-year-old first-time user as the anchor case. If the device cannot be used safely by that person, the design is wrong. This is not a lowest common denominator argument. It is a regulatory argument anchored in MDR Annex I §22. The manufacturer must prove the device works for the weakest realistic user, not the strongest.

Step two is to recruit formative participants who actually resemble the use specification. Do not recruit from the team's network. Do not recruit from LinkedIn. Recruit through patient advocacy groups, primary care networks, or a recruitment agency that specialises in older participants. Budget for this. Tibor has seen the cost of a proper recruitment pay for itself ten times over when summative validation passes first time.

Step three is to design for one-step simplicity. Every optional configuration is a risk. Every hidden menu is a risk. Every feature only power users will find is a feature that will confuse a lay user who stumbles into it. Cut aggressively. For a home use device, the default state must be the safe state.

Step four is to treat the instructions for use as part of the design, not as a downstream deliverable. Annex I §23 requires the IFU to be understandable to the intended user. For a lay user, that means plain language, large print, a quick-start card, short videos where possible, and explicit warnings about the most likely use errors the formative evaluation uncovered.

Step five is to run summative validation with the same user profile you claim to serve. If your use specification names "adults 40 to 80," your summative panel must reflect that range, not only 35-year-old testers who were easy to schedule. The notified body will look at the demographics of the summative cohort. Tibor does.

Reality Check

  1. Does your use specification name a specific, honest population including age, sensory capability, cognitive load, literacy, digital literacy, and environment?
  2. Could a 70-year-old first-time user use your device safely, alone, in an average kitchen, with only the IFU and no human support?
  3. Have you recruited formative participants who actually resemble your intended user population, or participants drawn from your professional network?
  4. Does the default configuration of the device put the lay user in the safest state, or does safety depend on optional settings the user may never touch?
  5. Is the IFU written at a reading level appropriate for the intended user, and has that reading level been validated, not assumed?
  6. Does your summative validation cohort reflect the demographic spread of the use specification, including the weakest realistic users?
  7. Have you explicitly cut features that only serve power users and that introduce risk for lay users who encounter them by accident?

Frequently Asked Questions

What counts as a "lay person" under MDR Annex I §22? MDR Article 2(38) defines a lay person as an individual who does not have formal education in a relevant field of healthcare or medical discipline. For Annex I §22 purposes, this means anyone who is not a trained healthcare professional using the device in the course of their practice. A nurse using a device at home to treat themselves is still a professional in most readings, but Tibor's advice is to treat any self-use scenario as lay use for usability purposes unless there is a strong reason not to.

Do I need a clinical investigation for a home use device? Not automatically. Annex I §22 is a usability and performance obligation, not a clinical evidence obligation. The clinical evaluation requirements are governed by MDR Article 61 and Annex XIV. Some home use devices will need clinical investigation, and most will need clinical evaluation, but §22 itself is about usability and appropriate performance for lay users, not clinical data.

How many participants do I need in a home use summative study? EN 62366-1 does not mandate a fixed number. Notified bodies commonly expect around 15 users per distinct user group. For home use devices, distinct user groups often include "primary user" and "caregiver," and may include age-stratified groups if the population spread is wide. A 15-participant study that is all young technology-comfortable testers is not a valid summative for a device intended for the elderly.

Can I rely on training to compensate for poor usability? Annex I §5 explicitly limits reliance on training as a risk control. Training can reduce residual risk but cannot replace design and labelling as the primary means of risk reduction. For lay users who receive little or no training, training-based risk controls are especially weak, and notified bodies are right to challenge them.

What if my use specification excludes users over 70? You can narrow the intended user population, but the narrowing must be enforced by the labelling and the distribution channel, and it must be justified. If your device is sold over the counter or prescribed broadly, restricting the intended use to "adults under 70" will not protect you if an 80-year-old buys it and uses it unsafely. The foreseeable misuse analysis under EN 62366-1 clause 5.6 has to cover this.

How does Annex I §22 interact with the IFU obligations in §23? They run together. §22 requires the device to perform appropriately for lay users. §23 requires the information supplied with the device to be understandable to the intended user. For a home use device, the two obligations are inseparable. A device that performs well only if the IFU is read carefully, by a user who will not read it carefully, is not compliant under §22.

Sources

  1. Regulation (EU) 2017/745 on medical devices, consolidated text. Article 2(38), Annex I §5, §22, §23.
  2. EN 62366-1:2015+A1:2020, Medical devices – Part 1: Application of usability engineering to medical devices.
  3. EN ISO 14971:2019+A11:2021, Medical devices – Application of risk management to medical devices.