Risk of acute kidney injury after hypertensive disorders of pregnancy: a population-based cohort study

Rationale and Objective — Though studies have demonstrated a relationship between hypertensive disorders of pregnancy (HDP) and chronic kidney disease, there are limited data on the risk of acute kidney injury (AKI) following HDP. We examined the risk of AKI following the occurrence of HDP.

Study Design — Retrospective population-based cohort study.

Setting and Participants — Pregnant women of Ontario, Canada, aged 14-50 years who delivered at ≥ 20-weeks gestation between April 1, 2002 and March 31, 2015.

Exposure — Preeclampsia, gestational hypertension, or neither.

Outcomes — The primary outcome was AKI with receipt of dialysis (AKI-D) ≥ 90 days after delivery. The main secondary outcome was AKI based on a hospitalization with a diagnostic code for AKI ≥ 90 days after delivery.

Analytical Approach — Time-dependent Cox proportional and cause-specific hazards models were used to evaluate the relationship between HDP and outcomes of interest. Models were adjusted for baseline and time-varying covariates.

Results — Our cohort comprised 1,142,656 women and 1,826,235 deliveries, of which 1.7% were associated with gestational hypertension and 4.4% with preeclampsia. After a mean follow-up of 6.7 years, there were 322 episodes of AKI-D (0.41 per 10,000 person-years), and 1598 episodes of AKI based on diagnostic codes (2.04 per 10,000 person-years). After adjustment, neither preeclampsia nor gestational hypertension was associated with AKI-D. Preeclampsia was associated with AKI (HR 1.22, 95% CI 1.03-1.45) but gestational hypertension was not.

Limitations — Retrospective design and possible unmeasured confounding. Cases of HDPs and AKI may have been undetected.

Conclusions — Preeclampsia was a risk factor for AKI occurring ≥ 90 days after delivery. Our findings suggest the potential importance of obtaining a pregnancy history as part of a comprehensive risk profile for acute kidney disease and suggest that women with a history of HDP may benefit from monitoring of kidney function.