Validation of the obstetric comorbidities index for predicting maternal mortality and severe maternal morbidity in South Korea.

To validate the Obstetric Comorbidity Index (OB-CMI) and estimate its predictive and discriminative performance for maternal outcomes in the South Korean population. This study used data on births from the National Health Insurance Service Delivery Cohort database in South Korea. The data on pregnant people who gave birth during 2003-2019 were included. The obstetric comorbidities were identified using the Bateman's OB-CMI. The outcomes were severe maternal morbidity (SMM) as defined by the CDC in the US; severe acute maternal morbidity (SAMM), as defined by EURONET; and maternal death within 30 days postpartum. The predictive and discriminative abilities of the index were calculated using the Brier score and area under the receiver operating characteristic curve (AUC). Of 6,527,810 births, 143,392 (2.2%), 84,994 (1.3%), and 555 (< 0.1%) resulted in SMM, SAMM, and maternal death, respectively. The predictive ability and discriminative performance of the OB-CMI were moderate and good (Brier scores of 0.02, 0.01, and 0.00 and AUC of 0.72, 0.68, and 0.78 for SMM, SAMM, and maternal death, respectively). The OB-CMI demonstrated moderate and good predictive and discriminative performance for SMM, SAMM, and maternal mortality in the South Korean population. These findings align with previous research, supporting OB-CMI as a valuable tool for identifying high-risk pregnancies.