Chae D, Kim SY, Song Y, et al. - Given that the most common side-effect of opioid-based intravenous patient-controlled analgesia is postoperative nausea and vomiting and some limitations of Apfel's simplified risk score do exist, therefore, researchers constructed and sought validation for a dynamic predictive model for nausea or vomiting up to 48 postoperative hours. This model is available as an online web application. They randomly categorized 22,144 adult patients who received fentanyl for analgesia following non-cardiac surgery under general anaesthesia, into development (80%) and validation (20%) cohorts, repeated 100 times. In order to choose variables for multivariate logistic regression, they used linear discriminant analysis. As for postoperative nausea or vomiting, the estimated incidences were: 0–48 h, 5691/22,144 (26%); 0–6 h, 2749/22,144 (12%); 6–12 h, 2687/22,144 (12%); 12–18 h, 2624/22,144 (12%); 18–24 h, 1884/22,144 (9%); and 24–48 h, 1082/22,144 (5%). The web application proposed in this study displayed utility to serve as a tool for clinicians to calculate incidences of nausea and vomiting in patients receiving intravenous fentanyl for patient-controlled analgesia.