Inter-operator variability in pPOSSUM scores: a note of caution

Purpose:Predicting perioperative morbidity and mortality can be achieved by several risk predicting algorithms. In the UK, the National Emergency Laparotomy Audit, mandated for all patients undergoing emergency laparotomy, uses pPOSSUM as its risk prediction tool. However, there is no literature reporting the inter-operator variability in calculating the score. Inter-rater variability was assessed based on 10 real general surgical cases that went on to have an emergency laparotomy.Methods:Forty clinicians, 10 each of registrars and consultants in anaesthetics and general surgery, were asked to calculate the pPOSSUM based on the clinical information typically available at the time of making the decision to proceed to emergency laparotomy for the same 10 National Emergency Laparotomy Audit cases. All participants were surveyed to assess their understanding and use of the pPOSSUM score.Results:More than 80% of respondents stated that they use pPOSSUM in daily clinical practice. There was variability in the calculated scores between the groups analysed. Two subgroups were evident: one in which the calculated mean pPOSSUM was similar between participants but did not reflect the true value, and the other which was accurate, but demonstrated high inter-rater variability.Conclusions:This is the first study to investigate inter-operator variability in pPOSSUM scores. Previous reports on the validity of the tool fail to account for subjective variation. At a time where pPOSSUM has become a routine part of clinical practice, this variability needs to be accounted for and taken into consideration in the decision-making process.