Preeclampsia and ESRD: The Role of Shared Risk Factors.

BACKGROUND

Several registry-based studies, using diagnostic codes, have suggested that preeclampsia is a risk factor for end-stage renal disease (ESRD). However, because the 2 diseases share risk factors, the true nature of their association remains uncertain. Our goals were to conduct a population-based study to determine the magnitude of the association between preeclampsia and ESRD and evaluate the role of shared risk factors.

STUDY

DESIGN

Population-based nested case-control study.

SETTING &

PARTICIPANTS

The US Renal Data System was used to identify women with ESRD from a cohort of 34,581 women who gave birth in 1976 to 2010 in Olmsted County, MN. 44 cases of ESRD were identified and each one was matched to 2 controls based on year of birth (±1 year), age at first pregnancy (±2 years), and parity (±1 or ≥4).

PREDICTOR: Preeclamptic pregnancy, confirmed by medical record review.

OUTCOME: ESRD.

MEASUREMENTS: Prepregnancy serum creatinine and urine protein measurements were recorded. Comorbid conditions existing prior to pregnancy were abstracted from medical records and included kidney disease, obesity, diabetes, and hypertension.

RESULTS

There was evidence of kidney disease prior to the first pregnancy in 9 of 44 (21%) cases and 1 of 88 (<1%) controls. Per chart review, 8 of 44 (18%) cases versus 4 of 88 (5%) controls had preeclamptic pregnancies (unadjusted OR, 4.0; 95% CI, 1.21-13.28). Results were similar after independent adjustment for race, education, diabetes, and hypertension prior to pregnancy. However, the association was attenuated and no longer significant after adjustment for obesity (OR, 3.25; 95% CI, 0.93-11.37).

LIMITATIONS: The limited number of ESRD cases and missing data for prepregnancy kidney function.

CONCLUSIONS

Our findings confirm that there is a sizable association between preeclampsia and ESRD; however, obesity is a previously unexplored confounder. Pre-existing kidney disease was common, but not consistently coded or diagnosed.