Usability Engineering for Medical Devices following ISO/IEC 62366

Medical devices are subject to highest security conditions. To avoid misuse we adapted our development process to be compliant with the ISO 62366.

Laboratory Information Systems (LIS) are applications in the medical environment and hence subject to highest security standards. Following the German ‘Medizinischer Dienst der Krankenversicherungen‘ in 2011 about 4000 accusation of patients prove true that they suffered from an error in treatment. Next to professional errors, these errors often originate from technical problems.

Diagnoses and therapeutic interventions rely on measurement results, analysis and information processing that done by hard- and software. These systems may contain errors and – like every other system – may deliver wrong results due to faulty use.

When creating medical devices, the ISO/IEC 14971 defines a procedure that allows manufactures to spot  dangers that arise from medical devices and to estimate these risks, judge and control them as well as to monitor the efficacy of this control. To gain a certification for the usability next to the prevention of technical errors, human errors have to be considered as well. The ISO/IEC 62366 demands that medical devices have to be developed following a usability process and all actions have to be documented.

Our client Swisslab GmbH produces one of the most comprehensive Laboratory Information Systems. The software has the goal to work efficient, stable and reliable and is through its modular structure adoptable to the individual needs of its users. A simple and clear handling eases the daily routine in the laboratory.

To continue to develop the Swisslab products in the spirit of the users, we supported Swisslab to introduce a development that follows the ideas of the ISO/IEC 62366 although SWISSLAB LIS is not certified as medical device according the ISO norm. The usability process following ISO/IEC 62366 consists of nine steps:

  1. Analyze Requirements:
    Often procurement contracts and requirements are held very short and are hence hard to understand for users and developers. As a consequence the actual tasks are supported insufficiently. During the requirement analysis the goal of the software is defined (Vision), the tasks are precisely described (Situationa) and it becomes clear who the actual user of the software is (Persona).
  2. Describe functions:
    Frequently used functions are identified and prioritized if necessary. To achieve this the Kano methodology can be used. It defines a) basic needs that are fundamental and taken for granted and users only become aware of when they are missing, b) performance needs that are obvious and create satisfaction or dissatisfaction and c) delighters, aspects that are surprising and value providing and make the product stand out of competing products and evoke enthusiasm.
  3. Identify risk potentials:
    The most central aspect of the standard is the reduction of human error. Its causes ave to be identified.
  4. Identify primary functions:
    Software contains a lot of supportive functions, that have to be separated from that actual requirements or POFs (primary operating functions). These POFs are in the focus of doing usability work. Particularly  these functions have to be tested to provide a safe and effective usage.
  5. Evolve Usability Specifications:
    Now the interface gets described, testable requirements are created and scenarios are developed that provide the picture for the actual use.
  6. Create research plan:
    Based on the specifications a plan has to be created how the interface and the work flow can investigated. Included should be information about who is conducting the test, how many people should be involved and which methodology will be used.
  7. UI Design:
    By aggregating all available information a testable suggestion for the UI is designed. This prototype may be interactive, respectively has to be interactive if interaction is an essential aspect.
  8. Verify UI:
    In this step it is checked whether the functions of the prototype match the requirements, whether the work flow fits the past experiences and whether the scope of functionality (POFs) is fully covered. Expert based methodology, e. g. Cognitive Walkthrough, can be used for this.
  9. Validate UI:
    Once the Ui is verified, it needs to be tested with users. The conditions of the test should match the natural work flow as good as possible, so users will work on the primary operations within the previously defined scenarios. Data relevant to the goals gets collected – in the case of medical devices primarily a misuse should ruled out.

Usability is an iterative process. Also the ISO/IEC 62366 arranges for an iterative repetition for these steps until all goals are met and an endangering is eliminated to the greatest possible extent. Furthermore a complete documentation is required. This documentation serves next to traceability also as a reference for future versions.

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