I know someone who is adamant that they can create a risk score combining user risk/operational risk/and downtime risk.
Not so sure about downtime. OK, it
could be factored in ... but I would only afford small values to it; so it would be swamped by other factors - life support, maintenance requirements, frequency/likelihood/seriousness of mishap
etc. - carrying far greater weight.
Downtime only really becomes a problem when considering "one-off" units (such as x-ray systems, and some lab equipment). But even then they can often be worked around by duplication of (or back-up) equipment, or co-operation with other hospitals.
In such cases, as the equipment is already "not working", the only risk to patients is delayed treatment.
So it's back to the drawing (black?) board, ivory tower ... wherever.
As I seemingly never tire of pointing out ... the key consideration is equipment
condition (see my tag-line).
