Obstetric co-morbidity index may predict maternal morbidity and need for transfer to better maternal care facility: Study

The obstetric comorbidity index (OBCMI) is a tool aimed at evaluating obstetric risk based on existing maternal and obstetric conditions. Patients receive scores reflecting their comorbidities, which are then totaled to create a numerical value. Initially developed for risk adjustment in extensive database analyses, the OBCMI has been commonly applied in research to characterize the acuity of study. Recent study conducted by McCarter et al. aimed to assess the relationship between the obstetric co-morbidity index (OBCMI) and severe maternal morbidity (SMM) in antepartum obstetric transfers to a Level IV maternal care facility. The study included antepartum transfers to a single Level IV maternal care facility from January 2016 to December 2020, focusing on deliveries that occurred during the same encounter. The OBCMI scores were retrospectively collected by manual chart review, and SMM was determined through ICD-10 and CPT code extraction confirmed by reviewers.

Correlation Between OBCMI and SM

Among the 561 transfers meeting the inclusion criteria, the study found a significant correlation between OBCMI and SMM. The median OBCMI was higher for transfers with maternal-only indications compared to fetal-only indications. The prevalence of SMM was notably different based on the indication for transfer. An OBCMI cutoff score of ≥ 4 was identified with high sensitivity (81%) in predicting SMM and was associated with adverse outcomes such as operative delivery, blood transfusion, ICU admission, prolonged hospitalization, and reoperation.

OBCMI Discrimination for SMM in Transfers

The study demonstrated that OBCMI could discriminate for SMM in obstetric transfers to a Level IV maternal care facility, especially for those transferred for maternal indications. However, the ability of OBCMI as a predictive tool decreased when stratifying transfers for fetal-only indications. The proposed OBCMI cutoff of ≥ 4 showed promising specificity and sensitivity in predicting SMM, indicating its potential usefulness in triaging obstetric patients for appropriate care.

Potential Value of OBCMI in Obstetric Transfer

Overall, the study highlighted the potential value of OBCMI as a tool to identify pregnant patients at a higher risk of SMM and adverse obstetric outcomes, particularly for antepartum transfers to Level IV maternal care facilities. The findings suggest that further validation and refinement of OBCMI, possibly through newer techniques like machine learning, could enhance its effectiveness as a predictive tool for ensuring risk-appropriate maternal care and triaging obstetric transfers effectively. Further studies are recommended to validate the OBCMI cutoff and assess its applicability across diverse populations and health systems.

Key Points

1. The study by McCarter et al. investigated the relationship between the obstetric co-morbidity index (OBCMI) and severe maternal morbidity (SMM) in antepartum obstetric transfers to a Level IV maternal care facility from January 2016 to December 2020. OBCMI scores were obtained through manual chart review, and SMM was confirmed using ICD-10 and CPT codes.

2. A significant correlation was found between OBCMI and SMM among the 561 transfers meeting the inclusion criteria. Higher OBCMI scores were observed in transfers with maternal-only indications compared to fetal-only indications. An OBCMI cutoff score of ≥ 4 showed high sensitivity (81%) in predicting SMM and was linked to adverse outcomes like operative delivery, blood transfusion, ICU admission, prolonged hospital stay, and reoperation.

3. OBCMI was found to effectively discriminate for SMM in antepartum transfers to a Level IV maternal care facility, especially in cases transferred for maternal indications. However, the predictive capability of OBCMI decreased when transfers were stratified for fetal-only indications. The proposed cutoff of ≥ 4 displayed promising specificity and sensitivity in predicting SMM, indicating its potential for effective triage of obstetric patients.

4. The study underscored the potential value of OBCMI in identifying pregnant patients at higher risk of SMM and adverse obstetric outcomes, particularly in antepartum transfers to Level IV maternal care facilities. It suggested further validation and refinement of OBCMI, possibly through advanced techniques like machine learning, to improve its efficiency as a predictive tool for ensuring appropriate maternal care and effective triage of obstetric transfers

5. The findings emphasize the importance of validating the OBCMI cutoff and evaluating its generalizability across different populations and health systems to enhance its utility in clinical practice. This implies that OBCMI could serve as a useful tool for risk assessment and management in antepartum transfers, aiding in the provision of tailored care for pregnant patients with heightened risks of SMM.

6. In conclusion, the study by McCarter et al. highlights the significance of OBCMI in predicting SMM in antepartum obstetric transfers to Level IV maternal care facilities and suggests the potential for its further development and integration into clinical practice to improve outcomes for pregnant patients at elevated risk of severe maternal morbidity.

Reference –

McCarter, A.R., Theiler, R.N., Branda, M.E. et al. The obstetrics comorbidity index as a predictive tool for risk-appropriate maternal care. BMC Pregnancy Childbirth 24, 797 (2024). https://doi.org/10.1186/s12884-024-06992-