Assessing the Incremental Value of Blood Oxygen Saturation (SpO(2)) in the miniPIERS (Pre-eclampsia Integrated Estimate of RiSk) Risk Prediction Model

Objective: To assess the incremental value of blood oxygen saturation (SpO(2)) as a predictor in the miniPIERS model, a risk prediction model for adverse outcomes among women with a diagnosis of hypertensive disorder of pregnancy (HDP) in low-resourced settings. Methods: Using data from a prospective cohort including 852 women admitted to hospital for a HDP, the association between SpO(2) and adverse maternal outcome was assessed using logistic regression. The miniPIERS model was recalibrated and extended to include SpO(2). The incremental value of adding SpO(2) to the model was measured using a net reclassification index (NRI), sensitivity, specificity, positive and negative predictive values, and likelihood ratios. Results: SpO(2) of < 93% was associated with a 30-fold increase in risk (95% CI 14 to 68) of adverse maternal outcome compared to women with SpO(2) > 97%. After recalibration and extension, the miniPIERS model including SpO(2) (vs. not including SpO(2)) had improved sensitivity (32.8% vs. 49.6%) at the cost of minimally decreased specificity (91.5% vs. 96.2%) with a NRI of 0.122. Conclusion: SpO(2) is a significant independent predictor of risk in women with a HDP. Adding SpO(2) to the miniPIERS model improved the model's ability to correctly identify high-risk patients who would benefit most from interventions.