BACKGROUND: Preoperative stress might influence postoperative pain, thereby, it is desirable to assess it more precisely. Thus, we developed and evaluated the psychometric properties of a brief measure of emotional preoperative stress (B-MEPS) index using Item Response Category Characteristic Curves. We validated and assessed whether the B-MEPS can predict moderate to intense acute postoperative pain (MIAPP).METHODS: We included 863 adult patients who underwent elective surgeries (ASA I-III physical status). The B-MEPS was constructed based on items selected from instruments to assess anxiety, depression, future self-perception and minor psychiatric disorders. We identified 24 items with greatest discriminant power to identify patients who should undergo surgery to treat cancer with MIAPP. The reliability was maximized using the Cronbach's alpha indices. Fifteen items remained, which were adjusted by the Generalized Partial Credit Model. The convergent validity was assessed correlating the B-MEPS index with the pain catastrophizing (n=100). Finally, the B-MEPS was applied in a prospective cohort of patients who underwent an abdominal hysterectomy (n=150).RESULTS: The Cronbach's alpha for selected items was 0.83. The correlation coefficient between B-MEPS index and catastrophizing was r=0.37 (P<0.01). A hierarchical regression model evidenced that the B-MEPS index was a factor independent to predict MIAPP after an abdominal hysterectomy [odds ratio (OR)=1.20, confidence interval (CI) 95% 1.05-1.43).CONCLUSIONS: The B-MEPS index presents satisfactory psychometric evaluations based on its internal consistency, convergent, and discriminant validity. The B-MEPS is a propensity index to MIAPP, which might help the clinician to decide on the best therapeutic approaches for acute postoperative pain.