Apfel's simplified score may favourably predict the risk of postoperative nausea and vomiting

Abstract

Purpose: To compare two of the latest published scores for predicting postoperative nausea and vomiting (PONV) in potentially high-risk patients. Methods: Adult in-patients scheduled for throat, thyroid, breast or gynecological surgery under general inhalational anesthesia were studied prospectively over 24 hr for PONV. The latest published score considers four risk factors: female gender, previous history of PONV or motion sickness, non-smoking status and postoperative use of opioids (Apfel-score). The previously published score includes, in addition to these factors, duration, type of anesthesia and surgery (Sinclair-score). The two scores were compared by calculating the area under a receiver operating characteristic (ROC)-curve and plotting calibration curves of the predicted and the observed incidence of PONV. Results: Five hundred consecutive patients were studied and patients who received prophylactic antiemetics were excluded. Of the remaining 428 patients 49.5% suffered from PONV. Multivariable analysis revealed that age, gender, previous history of PONV or motion sickness and postoperative use of opioids had an impact on PONV. The area under the ROC-curve was significantly greater for the Apfel-score compared to the Sinclair-score (0.71 vs 0.64, P=0.008). The correlation between the predicted (x) and the observed (y) incidence for the Apfel-score and for the Sinclair-score was y=1.08x - 0.07 and y=0.93x + 0.27. Conclusion: In our hospital, the simplified Apfel-score presented with favourable discriminating and calibration properties for predicting the risk of PONV. Therefore, we have implemented this score in our daily clinical practice as well as in an ongoing antiemetic trial.