New Data on Stroke Incidence Rates by Race

The overall incidence of stroke and ischemic stroke (IS) decreased among both White and Black people over the past two decades, results of an updated analysis of stroke trends in a representative US population showed.

However, the study showed persistent racial disparities, with incident stroke rates 50%-80% higher in Black people than in their White counterparts. Incident stroke also occurred at an earlier age in Black patients than in White patients (mean age, 62 years vs 71 years, respectively).

“We found that the rate of stroke is decreasing over time in both Black and White people — a very encouraging trend for US prevention efforts,” lead author Tracy E. Madsen, MD, PhD, Department of Emergency Medicine, Alpert Medical School, and Department of Epidemiology, School of Public Health, Brown University Providence, Rhode Island, said in a press release.

“But there was an inequity from the beginning of the study, with the rate of stroke always being higher for Black people than their White counterparts. The disparity did not decrease in 22 years, especially among younger and middle-aged adults,” Madsen added.

The findings were published online on January 10, 2024, in Neurology.

Researchers used data on stroke incidence between 1993 and 2015 from the Greater Cincinnati Northern Kentucky Stroke Study, a stroke surveillance study of adult residents that records stroke cases over a full year every 5 years.

Stroke cases were subtyped as IS, intracranial hemorrhage (ICH), or subarachnoid hemorrhage (SAH). Incidence rates were calculated per 100,000 individuals using US census data, and information on patient demographics and comorbidities were obtained from electronic patient records. Events with symptoms lasting

Investigators found the mean age of those with incident stroke decreased over time for both study groups. Between 1993 and 2015, it decreased from 66.1 to 61.7 years for Black people (P = .0004) and from 72.4 to 70.6 years for White people (P

Hypertension and diabetes increased over time in both groups, with the proportion of both conditions higher in Black individuals in all study periods. In 2015, 87% of Black people had hypertension and 43% had diabetes vs 76% and 30%, respectively, in White individuals.

Atrial fibrillation increased over time only in White people (P

Decrease in All Stroke Types

From 1993 to 2015, overall incidence of any type of stroke dropped from 230 to 188 per 100,000 (P = .011). IS cases also decreased, from 202 to 163 per 100,000 (P = .009).

Over that period, overall stroke rates decreased in White people from 215 to 170 per 100,000 (P = .015), and IS incidence dropped from 191 to 149 per 100,000 (P = .013).

These rates also declined in Black individuals, but the decrease was only significant for strokes of any type (349 to 311; P = .015).

The incidence of ICH was stable over time in the combined population and in the race-specific subgroups. SAH incidence decreased in the combined groups and in White people.

Black individuals had higher stroke incidence than White individuals, with incidence risk ratios ranging from 1.52 in 1999 to 1.83 in 2015 (P = .13 for trend over time).

Concerning Trends

An analysis of stroke incidence by age group showed rates in Black patients were highest in ages 20-34 vs 35-44 in White patients. There was no significant difference by race in stroke incidence at age 75 and older.

These results illustrated “concerning trends” and emphasized “the urgent need for increased attention to systemic racism in the healthcare system, inequities in access to care, improved primary prevention efforts, and the need for increased attention to social determinants of health,” the authors wrote.

Looking at 30-day case fatality by race over time, results showed rates were stable for strokes of any type and for IS in the combined group and for Black and White subgroups. There was a trend toward rising rates following ICH, especially among White people, and decreasing rates following SAH, again only in White people.

Due to potential variability in how data were collected across hospitals, it is possible there were race misclassifications and key social constructs that contribute to racial inequities that were not captured. In addition, the study only examined inequities in stroke incidence in only Black and White people. Other minorities were not included.

The study was funded by a grant from the National Institute of Neurological Disorders and Stroke (NINDS). Madsen received funds from NINDS and the National Heart Lung and Blood Institute. Full disclosures are available in the original article.