Blacks hospitalized for strokes in the District are one-third as likely as whites to receive lifesaving treatment, according to a study that seeks to understand racial disparities in treatment.

The findings, published online Thursday in the journal Stroke, offer a detailed look at the problem in a predominantly black urban population. Previous studies have shown that such disparities exist during treatment at a hospital. Researchers wanted to know why, so they surveyed stroke treatment by race at all seven acute-care hospitals in the District. Their findings, collected across an entire city with a large black population, are likely to have relevance for other predominantly black urban areas across the country.

Researchers found that blacks are significantly less likely to get the stroke treatment medication tissue plasminogen activator (tPA) because they don’t arrive at the hospital early enough, and even when they get there in time, they often have other risk factors, such as high blood pressure, that make them ineligible for the medication. The drug increases the risk of bleeding into the brain. To be effective, the medication also needs to be given within three hours of the onset of symptoms.

“Based on our data, it appears that much of the explanation is due to things that happen before the patient gets to the hospital,” said Amie Hsia, the lead author and medical director of Washington Hospital Center’s Stroke Center. The research was conducted by Georgetown University Medical Center.

That is good news for patients and their families, because they can increase the likelihood of getting treated with a few simple steps.

At the first hint of symptoms, call 911 and get to the hospital quickly. Control risk factors, such as high blood pressure, “so that it doesn’t become a factor in [preventing] safe treatment,” Hsia said.

At the same time, of the 45 patients who received treatment in the study, researchers found no racial bias. Seventy percent of the black patients received treatment, compared with 76 percent of whites. The finding is important, because previous studies have suggested that racial bias was a concern.

“When you hear about disparities in treatment rates for stroke patients, some might worry and ask, ‘Is it because of racial bias?’ — and you want to try to tease that out,” Hsia said.

Using the findings, community coordinators have been holding education sessions at D.C. churches, senior centers, health fairs, schools, even venues where taxi drivers congregate, said Chelsea Kidwell, director of Georgetown University Hospital’s Stroke Center.

Addressing the long-standing distrust of health systems among some African Americans, the coordinators point out that research shows no bias in stroke treatment, she said. Audiences are told about the treatment and that those who don’t control their high blood pressure put themselves “at risk for strokes down the road, and you also may be prevented from getting the one proven treatment that can reverse symptoms of a stroke,” Kidwell said.

Strokes are the fourth leading cause of death in the United States. A stroke occurs when a blood vessel in or leading to the brain bursts or is blocked by a blood clot, depriving the brain of oxygen. Depending on the severity of the stroke, immobility or paralysis might occur.

In the United States, the rate of first strokes in African Americans is almost double that of whites, researchers say, because of higher incidences of risk factors such as high blood pressure and obesity. And strokes tend to occur earlier in life for African Americans.

The research team reviewed 973 records from stroke patients hospitalized at Washington Hospital Center, Georgetown University Hospital, George Washington University Hospital, Sibley Memorial Hospital, Providence Hospital, Howard University Hospital and United Medical Center from Feb. 1, 2008, to Jan. 31, 2009.

Of the 775 black stroke patients, only 26, or 3 percent, received the clot-busting treatment tPA. By comparison, of the 198 white patients, 19, or nearly 10 percent, received the medication.

Getting to the hospital in time was a huge factor. Only 13 percent of black patients arrived within the critical three-hour window, compared with 21 percent of white patients. Of those patients who arrived in time, blacks were less likely to be eligible for the tPA treatment for a variety of reasons, such as having mild stroke symptoms, having had a stroke within three months and having extremely high blood pressure.

Kelvin Johnson, 52, had a stroke and arrived at Washington Hospital Center on June 18, but not in time for the clot-busting medication, said Hsia, who was among the doctors who treated him. Johnson, who has had two previous strokes, said he had trouble sleeping the night before and woke up that morning with weakness in his left arm and difficulty swallowing.

Because he awoke with the symptoms and doctors couldn’t pinpoint when they began, he was ruled out for tPA. Even if he had gotten to the hospital in time, his high blood pressure was problematic.

Johnson said he was generally aware of the importance of getting to the hospital within three hours but said he had never been told by his previous doctor about the specific stroke treatment or that his high blood pressure could make him ineligible for it.

He has received new medications to control his blood pressure. “I’m going to try to be as diligent as possible” in taking them, he said.