Interpretation of the four risk factors for postoperative nausea and vomiting in the Apfel simplified risk score: an analysis of published studies

Abstract

Purpose: The Apfel simplified risk score, developed in 1999, is the most widely used tool for risk stratification of postoperative nausea and vomiting (PONV). It includes four risk factors: female sex, non-smoking status, history of PONV or motion sickness, and use of postoperative opioids. Nevertheless, there is considerable heterogeneity in the definition and application of these risk factors in PONV research. Our aim was to determine how these risk factors are implemented in studies employing the Apfel score. Methods: Citations of the index Apfel score paper between 1 September 1999 and 1 September 2019 were identified in the Scopus database. Original full-text reports in English measurin..