Higher Risk for Repeat Hemorrhagic Stroke in Minorities

Batya Swift Yasgur, MA, LSW

June 11, 2018

Black and Hispanic people are substantially more likely than whites to have a recurrence of intracerebral hemorrhage (ICH), new research shows.

Investigators analyzed data from two studies of over 2000 people who had an ICH. One study followed patients for 1 year after the ICH, while the other followed patients for 4 years.

Black people were over twice as likely as white people to have another ICH, while Hispanic people were about 70% more likely.

These findings persisted even after adjustment for differences in blood pressure (BP), with black people remaining almost twice as likely, and Hispanic people about 50% more likely, to have a recurrence.

"The most immediate take-home message is that minority patients who have had hemorrhagic stroke are at very high risk and need to be followed closely to guarantee that blood pressure is adequately and stably controlled," study author Alessandro Biffi, MD, assistant professor of neurology, Massachusetts General Hospital, Boston, told Medscape Medical News.

"There are also important public health implications, given that hypertension did not account for all the differences between ethnic and racial groups, which is that there are unmeasured aspects of ICH risk that must be considered when delivering healthcare to minorities."

The study was published online June 6 in Neurology.

Expected Explanation?

Primary ICH is responsible for the majority of stroke-related morbidity and mortality, and ICH survivors are at "extremely high risk" for recurrent ICH, which is often fatal, the authors write.

Treatment of hypertension by controlling BP is the "cornerstone" of secondary ICH prevention. But while previous research has highlighted the potential role of elevated long-term BP variability, studies investigating the association with ICH recurrence risk, especially in black and Hispanic people, are lacking.

"We already knew that there is increased risk for black and Hispanic patients to develop a first ICH, but we didn't know much about a second one — and yet, that is quite frequent and usually devastating for these patients who already had a first stroke," Biffi said.

"We wanted to figure out whether the expected explanation — less well-controlled hypertension — is the answer, which would increase our understanding of ICH biology as well as potentially informing future guidelines for secondary ICH prevention that would incorporate race and ethnicity," he said.

To investigate the question, the researchers analyzed follow-up data of primary ICH survivors enrolled in two separate large studies of ICH: the longitudinal study conducted at Massachusetts General Hospital (MGH)  and the Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) study.

Participants were required to be age 18 years or older and diagnosed with acute primary (ie, spontaneous) ICH, including intraparenchymal bleeding occurring in the setting of oral therapeutic anticoagulation.

Baseline data collected at the time of enrollment included demographic information and medical history.

Patients (n = 2291) were identified as white (n = 1121), black (n = 529), Hispanic (n = 605), and other race/ethnicity (n = 36).

Longitudinal follow-up was conducted at 3, 6, and 12 months after the first ICH for both studies, but for the MGH-ICH study, participants and their caregivers were also contacted every 6 months after the first year from index ICH for an average of 4 years.

Follow-up BP was based on the most recent BP measurement conducted in a medical setting by medical personnel or obtained from analysis of the patient's medical records.

More Frequent Follow-up

Of 1532 participants on the ERICH study, 39 were lost to 12-month follow-up

(2.5% per year). Among the remaining participants, the annual recurrence rate was an estimated 1.5% (95% confidence interval [CI], 0.8% - 2.7%).      

Of the MGH-ICH group (n = 759), 55 were lost to follow-up at 49.8 months (1.5% per year). The estimated annual recurrence rate was 3.9% (95% CI, 2.5% - 5.9%).

The researchers began by examining potential systematic differences in hypertension severity (average systolic BP [SBP]/diastolic BP [DBP], SBP-variation coefficient [VC], and DBP-VC) between white, black, and Hispanic patients.

They found that average SBP during follow-up was higher for black (median, 149 mm Hg; interquartile range [IQR], 140 - 165 mm Hg; P = .009) and Hispanic (median, 146 mm Hg; IQR, 141 - 155 mm Hg; P = .011) compared with white ICH survivors (median, 141 mm Hg; IQR, 135 - 145 mm Hg).

Moreover, SBP variability (SBP-VC) was also higher for black and Hispanic ICH survivors, as compared to white individuals.

Across both studies, white ICH survivors had fewer recurrences than did black or Hispanic survivors (1.7% vs 6.6% and 6.1% respectively).

Yearly estimated ICH recurrence rates were 1.1% (IQR, 0.7% - 2.1%) for white, 3.9% (IQR 3.2% - 4.4%) for black, and 3.5% (IQR, 2.8% - 4.2%) for Hispanic ICH survivors.

Univariable analyses revealed that race/ethnicity, education level, prior ICH (before index event), ICH location, and ICH volume were associated with ICH recurrence.

SBP turned out to be a more important factor than DBP in risk for ICH recurrence, with higher SBP associated with increased risk (P = .039).

Greater SBP-VC was also associated with increased ICH recurrence risk.

After adjustment for BP measurements and variability, Hispanic (hazard ratio [HR], 1.51; 95% CI, 1.14 - 2.00; P = .004) and black (HR, 1.98; 95% CI, 1.36 - 2.86; P < .001) patients remained at higher risk for ICH recurrence than did white patients.

"Of note, exposure to antihypertensive agents during follow-up was not associated with ICH recurrence…and did not substantially modify observed results," the authors comment.

"We found out that, yes, black and Hispanic people have a higher average BP that also tends to vary more," Biffi commented.

"But, even accounting for that observation, these minorities are still at higher risk, pointing to a substantial gap in understanding how we should guide secondary stroke prevention for this group," he said.

He noted that this patient population may need to be followed more frequently than every 6 months.

"Maybe we should capture BP every 3 months, or by home telemonitoring technology, which is more sophisticated," he suggested.

He added, "We don't understand the genetic and biological aspects, but we know there are disparities, such as access to and quality of healthcare, health literacy, psychosocial stressors, and economic security, that likely play a role in increasing the risks for this population."

Unmeasured Factors

Commenting on the study for Medscape Medical News, Alexander A. Khalessi MD, MS, chairman of neurological surgery, UC San Diego Health, California, who was not involved in the study, said that it "uncovers the gap between the diagnosis of hemorrhage in the brain and the etiology of that hemorrhage."

The findings of the study demonstrate "posthemorrhage variation in BP in different ethnic groups, which implies potentially worse overall control, but still does not completely explain the different rates of repeat ICH between the racial and ethnic groups," he noted.

Additionally, there are strong socioeconomic and societal pressures, such as rates of tobacco use, differential access to primary care, and differences in how ethnic groups respond to medication management regimens, he explained, noting that African Americans tend to achieve better BP control with calcium channel blockers or angiotensin-converting enzyme inhibitors than with β-blockers.

"It is important when a person comes to the hospital with an ICH not just to treat the bleed but to establish cause and make sure the person has adequate access to healthcare," he said.

"There is room for further research into this healthcare gap, and we are pioneering an ongoing extension of this study to continue following enrolled white, black, and Hispanic patients to better understand the unmeasured factors that might still account for these disparities," Biffi added.

The study was funded by the National Institutes of Health (NIH). Biffi's work is supported by the NIH. The other authors' disclosures are listed with the original study. Khalessi has disclosed no relevant financial relationships.

Neurology. Published online June 6, 2018. Abstract

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