Blacks are more than twice as likely as whites to have clogged leg arteries, and no one knows why, researchers report.
The condition is called peripheral arterial disease (PAD). It affects arteries that bring oxygen-rich blood from the heart to the arms, legs, abdomen, and neck. These blood vessels develop buildup of plaque on the inside that results in gradual narrowing of the vessels. This narrowing impedes the circulation of blood flow, which deprives oxygenated blood to areas that need it.
“For reasons that are still unclear, something related to African American ethnicity raises the risk of PAD,” says researcher Michael Criqui, MD, MPH, in a news release.
Criqui is a professor of medicine and a professor of family and preventive medicine at the University of California, San Diego (UCSD).
Doctors should keep the findings in mind, Criqui notes.
“Physicians decide which patients to check carefully for PAD based on their age and other risk factors,” he says.
”This research says that physicians need to be particularly alert to the possibility of PAD in their African American patients,” Criqui says.
Patients can also watch for symptoms. The earliest and most common symptom may be tightness or a squeezing pain in the calf, thigh, or buttock during exertion (such as walking). This pain is called claudication and is usually relieved with rest. When your muscles are being used, the demand for oxygen to these areas rises. If there are circulation issues, then your muscles will be deprived of oxygen and you will feel pain.
As PAD progresses, it can occur at times of inactivity, such as at bedtime, and is referred to as “rest claudication” or “rest pain.”
Other PAD symptoms can include decreased leg strength and function, poor balance while standing, cold and numb feet or toes, slow-to-heal sores, foot pain at rest, and erectile dysfunction.
Criqui’s study appears in Circulation. It included 2,343 current or retired UCSD employees. They all had health care coverage through the university.
Participants were white, black, Hispanic, or Asian. Their average age was 60 for the men and 59 for the women.
Participants were screened for clogged leg arteries. They were also checked for other heart hazards -- diabetes, smoking, high blood pressure, cholesterol problems, body mass index (BMI), and personal or parental history of heart disease.
PAD in African-Americans
PAD was found in 104 participants (about 4 percent) and was most common in blacks, men, and older participants.
PAD was found in:
--Nearly 8 percent of blacks (25 out of 322 blacks)
--About 5 percent of non-Hispanic whites (69 out of 1,401 whites)
--Less than 2 percent of Hispanics (six out of 341 Hispanics)
--Less than 2 percent of Asians (four out of 279 Asians)
Taking other information about medical history into consideration, the researchers calculated that blacks were 2.3 times as likely as whites to have PAD.
Blacks were as likely to have PAD as someone from another ethnic group who was 10 years older or who had smoked for 20 years, says Criqui.
There weren’t enough Hispanics or Asians to draw firm conclusions about any PAD differences between whites, Hispanics, and Asians, the researchers note.
Blacks were also more likely to have diabetes, high blood pressure, and greater BMIs. That didn’t change the results.
“It had been presumed that the excess of PAD in African Americans was due to a greater proportion of African Americans having diabetes and hypertension,” says Criqui.
“Even though we found a link with those conditions, we were surprised that they only explained part of the risk,” he continues.
PAD has also been linked to smoking. More whites than blacks in the study were smokers.
Risk Rose With Age
PAD increased dramatically with age. Every extra decade roughly doubled the risk of PAD, the study shows.
For instance, PAD was found in less than 2 percent of participants who were younger than 50. But one in 10 participants age 70 and older had PAD.
PAD was also more common among men than women. It was found in 6 percent of the men and 3.6 percent of the women.
By Miranda Hitti, reviewed by Louise Chang, MD
SOURCES: Criqui, M. Circulation, Oct. 25, 2004; vol 112. News release, American Heart Association. WebMD Medical Reference from Healthwise: “Peripheral Arterial Disease of the Legs: Overview.” WebMD Medical Reference from Healthwise: “Peripheral Arterial Disease of the Legs: Symptoms.”