Risk of severe maternal morbidity and mortality among pregnant patients with chronic kidney disease: Renal disease and severe maternal morbidity.

Background: Chronic kidney disease is a significant cause of adverse obstetric outcomes. However, there are few studies assessing the risk of severe maternal morbidity and mortality among patients with chronic kidney disease and no studies assessing the association between individual indicators of severe maternal morbidity and chronic kidney disease.

Objective: To evaluate the risk of severe maternal morbidity and mortality among pregnant patients with chronic kidney disease.

Study Design: This was a population-based, retrospective cohort study including U.S. delivery hospitalizations from 2010-2020 utilizing the Healthcare Cost & Utilization Project National Inpatient Sample database. Patients were identified as having a delivery hospitalization, chronic kidney disease, and severe maternal morbidity using International Classification Diagnoses codes (9 and 10 edition). The primary outcomes were severe maternal morbidity and mortality, as defined according to the Centers for Disease Control and Prevention criteria. Multivariate logistic regression analyses were performed to estimate adjusted relative risk and 95% confidence intervals of severe maternal morbidity and mortality among patients with chronic kidney disease. Subgroup analyses were performed by chronic kidney disease etiology, stage, race and ethnicity, and individual indicators of severe maternal morbidity.

Results: Among the 38,374,326 parturients in this study, 95,272 (0.2%) had chronic kidney disease. The risk of severe maternal morbidity was higher for those with chronic kidney disease (12.2% vs. 0.7%, aRR 6.4, 95% CI 6.0-6.8) compared to those without. Among severe maternal morbidity indicators, those with chronic kidney disease were at highest risk for acute renal failure (aRR 21.7, 95% CI 19.8-23.7) and sepsis (aRR 9.0, 95% CI 7.6-10.5). Chronic kidney disease was also associated with an increased risk of maternal death (aRR 4.1, 95% CI 2.9-5.8). Black individuals had higher adjusted population attributable fraction (aPAF) between severe maternal morbidity and chronic kidney disease (aPAF 4.0%, 95% CI 3.6-4.3). Increased risk of severe maternal morbidity was associated with all chronic kidney disease subtypes, stages, and a history of renal transplant. Maternal death was significantly associated with diabetic nephropathy, renovascular, and obstructive or unspecified renal disease (aRR 7.3-14.1), as well as stages 3-5 of chronic kidney disease and a history of renal transplant (aRR 15.5-32.6). Risk of severe maternal morbidity and mortality were similar in those with a history of renal transplant and those with stage 1 chronic kidney disease. The number needed to treat with renal transplant to prevent one severe maternal morbidity event or maternal death in those with stages 3-5 chronic kidney disease was 2.6 (95% CI 2.4-2.9) and 45.0 (95% CI 31.0-82.0), respectively.

Conclusion: Chronic kidney disease in pregnancy was significantly associated with severe maternal morbidity, mortality, and other adverse perinatal outcomes, warranting close surveillance and multidisciplinary management throughout pregnancy.