UTIs Linked to Stroke Risk in Women With Preeclampsia

Pauline Anderson

April 25, 2017

BOSTON — Infections, particularly urinary tract infections (UTIs), are associated with an increased risk for stroke in women with preeclampsia, results of a new population-based cohort study show.

"Urinary tract infections may turn out to be a risk factor that we could identify, treat, and prevent in this population, said Eliza C. Miller, MD, a vascular neurology fellow at Columbia University Medical Center, New York.

"The only way we're going to be able to tell this is to do a prospective study, but I think we should definitely be looking at this," she concluded.

Coagulopathies, prothrombotic states, and chronic hypertension are also associated with an increased risk for stroke among women with preeclampsia, the study showed.

"Preeclampsia is sometimes not on the radar of neurologists, but it should be," said Dr Miller at a session during the American Academy of Neurology 2017 Annual Meeting (AAN).

A multisystem disorder, preeclampsia is defined as new-onset hypertension after 20 weeks of gestation, dysfunction in another organ system, or cerebral symptoms (such as headache or visual symptoms).

Although the pathophysiology of preeclampsia is not completely understood, the condition complicates 3% to 8% of pregnancies, said Dr Miller. It has high morbidity and accounts for 12% of maternal deaths, she added.

"And if you do have cerebral symptoms, that automatically qualifies you as having severe preeclampsia."

Women with preeclampsia are six times more likely to have a stroke during pregnancy or the postpartum period compared with women who don't have preeclampsia. They're also at higher risk for stroke later in life and develop cerebrovascular disease earlier than women with no history of preeclampsia.

The most common cause of death in preeclampsia is intracerebral hemorrhage (ICH).

In this analysis, Dr Miller and her colleagues aimed to identify risk factors, ideally modifiable risk factors, among these women who are already at high risk for stroke.

From a state-wide administrative database that tracks inpatient admissions, researchers identified all women aged 12-55 years admitted with preeclampsia or eclampsia from 2003-2012 who had a cerebrovascular event of any type.

The study had two control groups: the first was matched for age, race and insurance status, and the second was matched for age, race and severity.

Of 88,660 women with preeclampsia or eclampsia, 197 had a stroke. The incidence rate of 222 per 100,000 deliveries in this population is consistent with prior research and is about six times higher than the incidence of stroke of about 34 per 100,000 deliveries in the general population, said Dr Miller.

Almost half (46%) of the strokes were hemorrhagic and within that hemorrhagic stroke group, more than half (56%) were ICH subtype, 39% were subarachnoid hemorrhages (SAH) and a small percentage were both ICH and SAH.

About two thirds of the strokes occurred postpartum, and 80% occurred after women were discharged from hospital with their baby, said Dr Miller. But many women were released with home services or needed rehabilitation. "There is a high morbidity in this population, which likely reflects a high proportion of hemorrhagic strokes," said Dr Miller.

Not all women survived. "It's quite sobering; you can see that 13% of our cases died in the hospital, which is a very high mortality in comparison to the 0.02% maternal mortality that was reported around the same time in the overall population."

The analysis showed traditional risk factors were associated with an increased stroke risk, such as chronic hypertension (adjusted odds ratio [OR], 3.2; 95% confidence interval [CI], 1.8 - 5.5), prothrombotic state (adjusted OR, 3.5; 95% CI, 1.3 - 9.2), and bleeding disorders (coagulopathy; adjusted OR, 3.1; 95% CI, 1.7 - 7.1).

The presence of an infection increased the risk 3-fold (adjusted OR, 3.0; 95% CI, 1.6 - 5.8).

"This was driven entirely by UTIs," commented Dr Miller. "Other types of infections were the same in both groups, but the number of UTIs was far higher in the cases than controls."

When the researchers stratified by severity, they found similar results. "The numbers came out different in that analysis, but we ended up with the same factors emerging," said Dr Miller.

Because the study was based on administrative data and  International Classification of Diseases, Ninth Revision, codes, which can be variable, some preeclampsia diagnoses may have been missed, said Dr Miller. She added that some codes don't distinguish between stroke subtypes.

Researchers need to better understand the pathophysiology of preeclampsia, especially as it relates to cerebrovascular disease, concluded Dr Miller.

"We would love to identify biomarkers" for women with preeclampsia at highest risk for stroke. "And ideally, we could develop screening tools and be able to prevent this devastating disorder."

Asked by a delegate how many of the women were taking aspirin, Dr Miller said the database she and her colleagues used doesn't track medications, which is another limitation of the analysis. It is possible, then, that women with a prothrombotic state may have been receiving anticoagulation, which would put them at higher risk for hemorrhagic stroke.

And responding to a query of whether there aren't already biomarkers for preeclampsia, Dr Miller agreed there are, but she added, "We don't have biomarkers that tell us who's going to have a stroke."

The study was supported by an American Medical Association Foundation Seed Grant; National Institutes of Health/National Institute of Neurologic Disorders and Stroke Stroke/Net Training Fellowship.

American Academy of Neurology 2017 Annual Meeting (AAN). Abstract S15.007 Presented April 24, 2017.

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