(803) Impact of labor and delivery unit acuity on labor length and risk of cesarean delivery

Extensive research has investigated the impact of individual patient- and hospital-level factors such as delivery volume on labor management and perinatal outcomes. Our objective was to understand the impact of labor and delivery unit acuity and patient volume on labor management.

Study Design:

This is a retrospective cohort study between 3/2021 and 11/2022 at 8 hospitals in an integrated healthcare system. All laboring patients with viable, liveborn deliveries with an admission Obstetric Comorbidity Index (OB-CMI) score recorded were included. We measured the association of unit acuity (mean patient OB-CMI score on a unit in a 24-hour period) on length of labor and cesarean delivery (CD) using multivariable linear and logistic regressions. Fixed effects for hospital were included, and standard errors were clustered by hospital. Models were adjusted for volume (number of deliveries in 24-hour period) and patient factors. These analyses were also performed in the subset of nulliparous patients with term, singleton, vertex-presenting fetuses (NTSV). As sensitivity analyses, we assessed other measures of unit acuity, including relative unit acuity, proportion of patients with OB-CMI >5, maximum OB-CMI, and unit presence of a patient with OB-CMI >5. 

Results:

There were 22,159 patients included, of which 11,766 (53.1%) were NTSV patients. In models with only hospital fixed effects, mean daily OB-CMI was associated with length of labor (β=1.21, 95%CI 0.40-2.01) and unscheduled CD (OR 1.18, 95% CI 1.12-1.23). The association was not affected by delivery volume. After adjusting for patient characteristics, there was no longer an association (Table 1). This pattern persisted for all alternate measures of unit acuity and among NTSV patients.

Conclusion:

In a large healthcare system, measures of daily unit acuity were not associated with length of labor or risk of CD after controlling for hospital- and patient-level factors. This suggests that despite higher patient acuity or delivery volume, unit resources can compensate such that other patients’ outcomes are unaffected.