The Predictive Value of Vital Sign Patterns for Morbidity in Pregnancy:
A Retrospective Cohort Study
Abstract
Objective. This study examined the predictive ability of established
Maternal Early Warning systems (MEWS) for different types of maternal
morbidity, in order to discern an optimal early warning system. Design.
Retrospective cohort study. Setting. Four-hospital urban academic
system. Population. All patients admitted to the obstetric services of
this hospital system in 2018. Methods. All patient vital signs were
collected and three sets of published MEWS criteria were evaluated in
relation to maternal morbidity. The test characteristics of each MEWS,
as well as for heart rate, blood pressure, and oxygen saturation
individually and in different combinations were compared. Main Outcome
Measures. Maternal morbidity, defined as a composite of hemorrhage,
infection, acute cardiac disease, and acute respiratory disease,
ascertained from informatics and administrative data. Results. Of 14,597
obstetric admissions, 2,451 patients experienced composite morbidity
(16.8%). The sensitivities (15.3% - 64.8%), specificities (56.8% -
96.1%), and positive predictive values (22.3% - 44.5%) of the three
MEWS criteria ranged. Of patients with any morbidity, 28% met criteria
for the most liberal vital sign combination, while only 2% met criteria
for the most restrictive parameters, compared to 14% and 1% of
patients without morbidity, respectively. Sensitivity of all vital sign
combinations was low (maximum 28.2%), while specificity ranged from
86.1 – 99.3%. Conclusions. Though all MEWS criteria demonstrated poor
sensitivity for maternal morbidity, permutations of the most abnormal
vital signs have high specificity, suggesting that MEWS may be better
implemented as a trigger tool to target more sensitive screening
techniques for maternal morbidity.