Does measurement of preoperative anxiety have added value for predicting postoperative nausea and vomiting?

Preoperative anxiety has been suggested as a predictor of postoperative nausea and vomiting (PONV), but supporting data are lacking. We quantified the added predictive value of preoperative anxiety to established predictors of PONV in 1389 surgical inpatients undergoing various procedures, by using multivariate logistic regression analysis. Investigated predictors were a history of PONV or motion sickness, smoking, sex, age, ethnicity, body mass index, ASA physical status, surgery type, duration of anesthesia, anesthetic technique, and postoperative opioid analgesia. Anxiety was measured by the Spielberger State-Trait Anxiety Inventory and the Amsterdam Preoperative Anxiety and Information Scale. The outcome was the occurrence of PONV in the first 24 h after surgery. The area under the receiver operating characteristic curve of a multivariate (logistic regression) model including sex, age, smoking, history of PONV or motion sickness, surgery type, and anesthetic technique was 0.72 (95% confidence interval, 0.70-0.74). There was a weak but significant association of anxiety with PONV, but the addition of anxiety to the model did not further increase the area under the receiver operating characteristic curve. Therefore, routine preoperative measurement of anxiety does not seem warranted, provided that the other predictors are already considered.