Temporal trends in risk of acute kidney injury among patients with preeclampsia in Canada: a retrospective cohort study [Research]

Background: Several studies have documented increasing rates of obstetric acute kidney injury (AKI) in Canada, particularly among females with preeclampsia. We aimed to quantify recent patterns in obstetric AKI and explore the cause for the rising rates.

Methods: We conducted a retrospective cohort study of all hospital deliveries in Canada (excluding Quebec) between April 2013 and March 2023, using data obtained from the Canadian Institute for Health Information. We estimated temporal changes in rates of AKI and pulmonary edema by province and hospital, and changes in markers of illness severity and gestational age - specific rates of AKI.

We quantified temporal trends in AKI rates, adjusted for risk factors, using logistic regression. Results: We identified 2 796 152 deliveries; 1710 patients developed AKI.

Rates of AKI increased from 3.92 per 10 000 deliveries in 2013 to 2014 to 7.84 per 10 000 deliveries in 2022 to 2023 among all deliveries, and from 109.9 to 160.1 per 10 000 deliveries among patients with preeclampsia (rate ratio 1.46, 95% confidence interval 1.07 to 1.99). Rates of pulmonary edema remained stable and showed a weak inverse association with rates of AKI among patients with preeclampsia.

Patients with preeclampsia, with and without a diagnosis of AKI, showed similar temporal changes in markers of illness severity. Rates of AKI increased at all gestational ages.

Adjustment for risk factors did not explain the temporal increase in rates of AKI among patients with preeclampsia. Interpretation: Rates of obstetric AKI increased substantially in Canada between 2013 and 2023, with spatiotemporal patterns suggestive of an underlying change in preeclampsia management.

Detailed clinical investigation is required to definitively explain and address the rising rates of obstetric AKI.