Lifetime Risk of PAD Varies by Race, but All Are Vulnerable to Traditional Risk Factors

Compared with white and Hispanic individuals, black men and women have about a 10% higher lifetime risk of developing PAD, according to a new risk-prediction tool created by combining data from some of the largest community-based cohorts in the United States.

Between birth and age 80, around three in 10 black individuals have an ankle-brachial index (ABI) below 0.90, researchers found. Among Hispanic and white patients, the proportion is two in 10.

Creation of a PAD prediction tool fills an important void, the study’s lead author, Kunihiro Matsushita, MD, PhD (Johns Hopkins Bloomberg School of Public Health, Baltimore, MD), told TCTMD.

Unlike coronary artery disease and stroke, for which there are lifetime risk-prediction tools, there currently are none for PAD. Moreover, knowing that differences by race exist is important knowledge for clinicians since even the 2016 American Heart Association/American College of Cardiology PAD guidelines give no indication that black race, for example, is a risk factor for PAD, he said.

As Matsushita and colleagues note in the paper, published online September 10, 2019, in the Journal of the American Heart Association, awareness of race-based risk as well as the timeline for disease development can guide preventive efforts and “is useful for communicating long-term risk and estimating the future burden of disease in populations.”

Useful Info for Clinicians and Patients

The investigators looked at ABI measurements across six well-known, long-term cohort studies—the Atherosclerosis Risk in Communities study, the Cardiovascular Health Study, the Framingham Heart Study, the Framingham Offspring study, the Multi-Ethnic Study of Atherosclerosis, and the National Health and Nutrition Examination Survey—for a study population totaling 38,154. The combined data revealed that while white men and women had a 19% lifetime risk of PAD, and Hispanic men and women had a 22% risk, the incidence was 30% in black men and 27.6% in black women. Asians were not included due to numbers too small to analyze.

The study also found that black individuals reach a 10% lifetime risk for PAD an average of 8 to 11 years earlier than whites or Hispanics. Smoking, diabetes, and a history of other cardiovascular disease all carried additional lifetime risk of PAD across all of the race/ethnicity groups, although the degree to which risk was augmented varied among the different combinations.

The risk calculator developed by Matsushita and colleagues uses values for age, gender, race, BP, cholesterol, history of CVD, as well as smoking and diabetes status to generate both a residual lifetime risk of PAD and a prevalence of PAD for individual patients.

“It can be used by clinicians to get a sense about lifetime risk and the risk of having PAD according to the combination of demographic and clinical factors,” Matsushita observed. “This can be useful in a risk discussion with patients,  particularly with the decision to move forward with an ABI test, for example.

In their paper, the researchers note that the calculator’s ability to account for individual combinations means that one black male may have a lifetime risk of PAD as high as 70% while another may have a risk lower than 20%, owing to them having very different risk-factor profiles.

“This is probably the first attempt to quantify the impact of all those things in the context of predicting risk of PAD,” Matsushita said. Having knowledge of risk in this way, he added, can help better guide prevention strategies and monitoring on an individual level.