This is the ninth in a series of blog postings in which we present a top-ten list of common errors encountered in the context of medical projects. Of course, such a ranking depends on personal observations and individual experience – and hence has a subjective outcome. Please feel invited to tell us about your perspective in the comments section!
Classification systems are helpful because they compress a lot of information into a small set of pigeon-holes. They allow us to treat objects with similar properties in similar ways – and to discuss them much more efficiently. Is is hence no surprise that the world of medical devices is full of classification systems, too: Different sources (e.g., laws and standards) define different sets of classes for different aspects. While this gives us all the advantages outlined above, the sheer multitude of dimensions also poses a challenge: People tend to confuse the different systems, to forget about their original definitions, and to ignore their areas of validity.
The result of this confusion and carelessness is classification gibberish – as exemplified by statements like “This is a class-C device”. Such a sentence may even sound smart to bystanders due to the technical term, but in fact, it makes about as much sense as “This is a horizontal melon”. After all, the classes A/B/C (as defined in the IEC 62304 standard) refer to the criticality of software systems and software units, not devices.
So what about the criticality of medical devices? This is the next pitfall because different legislations use different classification systems with similar names. For instance:
- For the EU, the Medical Device Directive (93/42/EEC) defines the classes I/IIa/IIb/III, where class I has two special variations known as Is and Im.
- For the US, classification procedures are defined in the Code of Federal Regulations, Title 21, part 860. The respective classes are I/II/III.
As a consequence, statements like “This is a class-I device” are feasible, but underspecified.
Alright, alright – let’s stick to the EU for now. What about the sentence “A pacemaker is a class-III device”? Is it still mistakable? Well, no… it is entirely wrong. A pacemaker is an active implantable device and therefore covered by the AIMD (90/385/EEC), not the MDD. This also shows that the two classification systems outlined above are not synonymous: In the US, a pacemaker is a class-III device.
Needless to say, classification gibberish exists for the US market as well. For instance, it is often suggested that there are two ways for medical devices to be marketed – namely the 510(k) process versus the Premarket Approval (PMA) process –, where the latter is only required for class-III devices. While this is true as a rule of thumb, it is definitely not true as a legal statement. For instance, well-known types of low-risk devices are 510(k) exempt (most of them class I), which in a sense gives us three instead of two regulatory pathways. Plus, on a historical note, there exist class-III devices for which no PMA was conducted.
As a final example, let us consider the software level of concern, which basically helps a manufacturer understand how much documentation he needs to include in a premarket submission to the FDA. Again and again, people try to equate the three levels of concern (minor, moderate, major) with the three safety classes defined by IEC 62304 (A/B/C), but they really are not synonymous at all.
Coming up next: #1, Accidentally Medical. See you there – or at the MedConf 2016!
- Top Ten Errors in Medical Projects – #3: Late Safety
- Top Ten Errors in Medical Projects – #4: Risk Analysis Gone Wrong
- Top Ten Errors in Medical Projects – #5: V for Vendetta
- Top Ten Errors in Medical Projects – #6: As Low As Reasonably Practicable
- Top Ten Errors in Medical Projects – #7: The 100% Confusion
- Top Ten Errors in Medical Projects – #8: Eager Beaver / Lazy Bum
- Top Ten Errors in Medical Projects – #9: Process versus Project
- Top Ten Errors in Medical Projects – #10: Clinical Something!