(242) Impact of unit acuity on postpartum hemorrhage and severe maternal morbidity

This is a retrospective cohort study between 3/2021 and 11/2022 at 8 hospitals and included laboring patients with viable, liveborn deliveries with an Obstetric Comorbidity Index (OB-CMI) score recorded on admission. We measured the association of unit acuity (mean OB-CMI score on a unit in a 24-hour period) on PPH and SMM using logistic regressions. Fixed effects for hospital were included to account for fixed hospital-specific characteristics, and standard errors were clustered by hospital. Models were adjusted for volume (number of deliveries in 24-hour period) and patient factors (OB-CMI, parity, and gestational age). We performed this analysis in a subset of patients at low risk of morbidity (OB-CMI ≤2). As sensitivity analyses, we assessed other measures of unit acuity (relative unit acuity, maximum OB-CMI, and unit presence of a patient with OB-CMI >5), and an outcome of non-transfusion SMM.

Results:

Of 22,159 patients included, 713 (3.2%) had SMM, and 1,921 patients (8.6%) had a PPH. In unadjusted models, mean daily OB-CMI was associated with PPH (OR 1.19, 95% CI 1.14-1.24) and SMM (OR 1.26, 95% CI 1.17-1.36). The association was not affected by delivery volume in a 24-hour period. However, after adjusting for patient factors, there was no association with SMM; the association with PPH was weak (Table 1). For the adjusted analysis in the low-risk cohort, unit acuity was not associated with PPH or SMM. This pattern persisted for alternative measures of unit acuity and for non-transfusion SMM.

Conclusion:

In a large healthcare system, measures of unit acuity were not associated with a patient’s risk of PPH or SMM after controlling for patient-level factors. This suggests individual outcomes are not significantly affected by unit acuity or volume, rather most risk is related to individual patient factors.