Risk Factors and Risk for Severe Maternal Morbidity in Severe Preeclampsia Complicated by Pulmonary Edema: A Case-Control Study

Objective The objective of this study is to examine risk factors and adverse outcomes related to preeclampsia with severe features complicated by pulmonary edema. Study Design This is a nested case-control study of all patients with preeclampsia with severe features who delivered in a tertiary, urban, academic medical center over a 1-year period. The primary exposure was pulmonary edema and the primary outcome was a composite of severe maternal morbidity (SMM), defined according to the Centers for Disease Control and Prevention and based on International Classification of Diseases, 10th revision, Clinical Modification codes. Secondary outcomes included postpartum length of stay, maternal intensive care unit admission, 30-day readmission, and discharge on antihypertensive medication. A multivariable logistic regression model adjusting for clinical characteristics related to the primary outcome was used to determine adjusted odds ratios (aOR) as measures of effect. Results Of 340 patients with severe preeclampsia, there were seven cases of pulmonary edema (2.1%). Pulmonary edema was associated with lower parity, autoimmune disease, earlier gestational age at diagnosis of preeclampsia and at delivery, and cesarean section. Patients with pulmonary edema demonstrated increased odds of SMM (aOR: 10.11, 95% confidence interval [CI]: 2.13-47.90), extended postpartum length of stay (aOR: 32.56, 95% CI: 3.95-268.45), and intensive care unit admission (aOR: 102.85, 95% CI: 7.43-1422.92) compared with those without pulmonary edema. Conclusion Pulmonary edema is associated with adverse maternal outcomes among patients with severe preeclampsia, and is more likely to affect patients who are nulliparous, have an autoimmune disease, and are diagnosed preterm.