A RISK SCORE TO PREDICT THE PROBABILITY OF POSTOPERATIVE VOMITING IN ADULTS

Background: The aim of this study was to identify factors most relevan t for postoperative vomiting (PV) and to develop a risk score to predi ct the probability of PV. Methods: Adult inpatients scheduled for elec tive ear, nose and throat (ENT) surgery under general anaesthesia were offered to participate in a prospective study for PV over 24 h. No pr ophylactic antiemetics were used. The data of 1137 patients were rando mized and split into an evaluation set (n=553) and a validation set (n =584). The evaluation set was subjected to logistic regression analysi s to quantify the relative impact of anaesthetic, surgical and individ ual factors and to develop a risk score. The score was then tested by applying it to the validation set. The area under a receiver operation characteristic (ROC) curve was calculated and the predicted and actua l incidences of patients were correlated. Results: In the evaluation s et, patient-related factors (female gender, young age, non-smoking, hi story of PV or motion sickness) and a high duration of anaesthesia wer e independent risk factors for PV. The probability of PV could be esti mated from the equation: PV=1/(1+exp(-z)) where z=1.28 . (gender)-0.02 9 . (age)-0.74 . (smoking)+0.63 . (history of PV or motion sickness)+0 .26 . (duration)-0.92. In the validation set this score achieved an ar ea under the ROC-curve of 0.78 and the actual incidence correlated str ongly with the predicted risks (R-2=0.93, P<0.001). Conclusion: The da ta suggest that the probability of PV following ENT surgery under inha lational anaesthesia with low-dose opioids can be predicted by a score mainly based upon patient-related risk factors.