Acceptable Risk – Easy to talk about, but no one knows what it means

May 4, 2008


Standards about risk management always talk about “acceptable risk.” This is a qualitative term. Unfortunately, for much of healthcare there is no matching quantitative assessment or goal. Consider two examples.



Precision is acceptable

CV is 8% and goal is 10%

Residual risk is acceptable




It is possible to estimate the probability of a severe adverse event and to have an associated goal for such a probability but no one in healthcare does this. So one will see things like, “with this mitigation we have reduced the risk of the adverse event to an acceptable level” but the reality is no one knows what this really means.

Never Events – Never a meaningful goal

May 3, 2008

problemThis has been considerable discussion about the National Quality Forum’s  so called 28 never events (1). Here are some problems with this concept.

Never is a poor goal – Adverse events can be considered within a risk management program. Risk is the combination of two items – severity and probability of occurrence. By their selection, one can gather than severity is high for the 28 events. However, probability can never be zero. Consider a simple example. The likelihood of performing wrong site surgery is X. One performs a double check to prevent wrong site surgery. Now the likelihood is 0.0001X. But the double check can fail. So one can perform a triple check. Now the probability is much lower but it is still not zero. And so on. Working with probabilities (as in fault trees), is one way to see that probabilities are never zero, nor is risk.

28 goals are too many – If one wants to manage anything, one needs a limited number of goals. There is no reason why one can’t combine events to give a single goal – the overall risk of an adverse event.

“largely preventable” is not the same as preventable – In the NQF site, the never events are said to be largely preventable. The problems with this are obvious.


1.       See