Probability of adverse events that have not yet occurred: a statistical reminder

E Eypasch, R Lefering, CK Kum, H Troidl - Bmj, 1995 - bmj.com
E Eypasch, R Lefering, CK Kum, H Troidl
Bmj, 1995bmj.com
The probability of adverse and undesirable events during and after operations that have not
yet occurred in a finite number of patients (n) can be estimated with Hanley's simple formula,
which gives the upper limit of the 95% confidence interval of the probability of such an event:
upper limit of 95% confidence interval= maximum risk= 3/n (for n> 30). Doctors and
surgeons should keep this simple rule in mind when complication rates of zero are reported
in the literature and when they have not (yet) experienced a disastrous complication in a …
The probability of adverse and undesirable events during and after operations that have not yet occurred in a finite number of patients (n) can be estimated with Hanley's simple formula, which gives the upper limit of the 95% confidence interval of the probability of such an event: upper limit of 95% confidence interval= maximum risk= 3/n (for n> 30). Doctors and surgeons should keep this simple rule in mind when complication rates of zero are reported in the literature and when they have not (yet) experienced a disastrous complication in a procedure.
Just as aeroplanes should not crash, common bile ducts should not be cut and iliac vessels not be punctured during laparoscopic procedures. In reality, however, these things do happen. 1 With the boom in endoscopic surgery, surgeons are claiming to have zero mortality or even zero morbidity in their series of operations. A little reminder, not only for surgeons, may be necessary. If a certain adverse event or complication does not occur in a series, it does not mean that it will never happen. Experience and Murphy's law teach us that catastrophes do happen, and their probability can in fact be calculated by a simple rule of thumb.
bmj.com