Assessing the incremental value of blood oxygen saturation (SpO(2)) in the miniPIERS (Pre-eclampsia integrated estimate of risk) risk prediction model

Document Type



Obstetrics and Gynaecology


Objective: To assess the incremental value of blood oxygen saturation (SpO2) 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 SpO2 and adverse maternal outcome was assessed using logistic regression. The miniPIERS model was recalibrated and extended to include SpO2. The incremental value of adding SpO2 to the model was measured using a net reclassification index (NRI), sensitivity, specificity, positive and negative predictive values, and likelihood ratios.

Results: SpO2 of < 93% was associated with a 30-fold increase in risk (95% CI 14 to 68) of adverse maternal outcome compared to women with SpO2 > 97%. After recalibration and extension, the miniPIERS model including SpO2 (vs. not including SpO2) 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: SpO2 is a significant independent predictor of risk in women with a HDP. Adding SpO2 to the miniPIERS model improved the model’s ability to correctly identify high-risk patients who would benefit most from interventions


Journal of Obstetrics and Gynaecology Canada