External validation of the POP score for predicting obstetric and gynecological diseases in the emergency department.

Abstract

The POP score was developed as an easy screening tool for predicting obstetrics and gynecological (OBGYN) diseases in the emergency department (ED), and consists of three predictors, each representing one point: past history of OBGYN diseases, no fever or digestive symptoms, and peritoneal irritation signs). However, its external validity has not yet been evaluated. We aimed to perform the external validation of the POP score. This is a multi-center, retrospective cohort study using ED data of three tertiary care hospitals in Japan between Jan 2017 and October 2020. Young adult women aged 16-49years with abdominal pain were included in the analysis. The probability of OBGYN diseases was calculated using a logistic regression model of the POP score. Predictions were compared with observations to evaluate the calibration of the model. Further, the diagnostic ability (sensitivity, specificity, and likelihood ratio) of the POP score was evaluated. Of 66,599 ED visits, 1026 young adult women (median age [interquartile range]: 31 [23-41] years) were included for the analysis. The c-statistic was 0.645 [95% confidence interval (CI): 0.603-0.687]. The predicted probabilities of OBGYN diseases was generally well-calibrated to the observations. When the cut-off was set between 2 and 3 points for the ruling in of OBGYN diseases, the positive likelihood ratio was 9.72 [95% CI: 3.33-28.4]. When the cut-off was set between 0 and 1 points for ruling out of OBGYN diseases, negative likelihood ratio was 0.181 [95% CI: 0.059-0.558]. Using ED data of three tertiary care hospitals, we externally validated the POP score for prediction of OBGYN diseases in the ED. The POP score likely has clinical value for screening OBGYN diseases in young adult women with abdominal pain in the ED.