What’s Behind Rising Rates of Obstetric Renal Failure?

Recent increases in obstetric acute renal failure are limited to women with hypertensive disorders of pregnancy, suggests a report in the British Medical Journal.

The retrospective analysis included nearly 2.2 million hospital deliveries in Canada, excluding Quebec, between 2003 and 2010. Based on ICD-10 codes, the rate of obstetric acute renal failure increased by 61 percent during this period: from 1.66 per 10,000 deliveries in 2003 to 2004 to 2.68 per 10,000 in 2009 to 2010. There was also a 21 percent increase in the rate of postpartum hemorrhage, along with a slight increase in risk of hypertensive disorders of pregnancy. However, the temporal trend in renal failure remained significant after adjustment for these and other risk factors.

On further analysis, the increase in obstetric renal failure occurred exclusively in women with hypertensive disorders of pregnancy. This group showed an adjusted increase of 91 percent: from 15.6 to 28.8 per 10,000 deliveries. The trend was even more pronounced among women who had gestational hypertension with significant proteinuria: adjusted increase 171 percent. Of 58 excess cases of acute renal failure in 2009 to 2010, 47 were in women with hypertensive disorders of pregnancy and 42 in women with gestational hypertension and significant proteinuria.

In both the United States and Canada, the rates of obstetric acute renal failure have increased over the past decade. This large analysis of Canadian data suggests that this trend is limited to women with hypertensive disorders of pregnancy, with an even sharper increase in the smaller group of women with gestational hypertension and significant proteinuria. These trends raise the possibility that some aspect of preeclampsia management may be leading to an increased risk of obstetric acute renal failure [Mehrabadi A, et al. Hypertensive disorders of pregnancy and the recent increase in obstetric acute renal failure in Canada: population based retrospective cohort study. BMJ 2014; 349:g4731].