Thank you for the opportunity to express our views regarding the USPSTF’s evidence review and draft recommendation statement for peripheral artery disease (PAD) and cardiovascular disease (CVD) screening with Ankle-Brachial Index (ABI). The National Center for Health Research is a nonprofit think tank that conducts, analyzes, and scrutinizes research, policies, and programs on a range of issues related to health and safety. We do not accept funding from companies that make products that are the subject of our work.
We agree with the USPSTF grade of “I” for ABI screening due to an inadequate amount and quality of evidence to conclusively determine the balance of benefits and harms. There have been no population-based randomized trials testing ABI screening alone, and the single “fair-quality” study that evaluated ABI’s efficacy found a very low sensitivity rate. According to the study, ABI screens provided an 80-85% false negative rate. This means that negative screens with ABI could lead to about 80% or more of patients having a false sense of reassurance about their risk of underlying peripheral artery disease. The poor sensitivity of ABI can be potentially harmful because patients may be inappropriately ruled out for underlying PAD and may miss out on an opportunity for follow up diagnostic testing and clinical interventions. These patients may not be properly diagnosed until symptoms are more apparent, which may be at a time when disease has progressed and outcomes are poor. This issue necessitates further study to better characterize subpopulations who are likely to benefit from ABI.
PAD is a fairly common condition and most adults do not present with symptoms. Moreover, the dangerous consequences of the disease, including loss of life and limb, create a compelling need to identify appropriate screening strategies to detect disease earlier and prevent disability. Unfortunately, the data regarding the ABI screening method is too scarce to make a definitive recommendation. While ABI is the most common method of screening for PAD, it may not be the most effective. The process of performing ABI takes around 15 minutes, but this time may be more effectively applied to other methods that have been tested and proven to be more beneficial.
In order to more widely recommend ABI, we need more studies directly evaluating both the efficacy and harms. Most importantly, we encourage the USPSTF to review studies that analyze the accuracy of ABI and its effect on improving health outcomes in asymptomatic PAD patients. It is critical to identify whether the benefits of ABI screening outweigh harms in high risk patients, such as patients who smoke, or have diabetes, as this population is likely to benefit the most from screening.
At this time, we agree that there is insufficient evidence to recommend for or against its use. We encourage the USPSTF to update their recommendations when additional high-quality evidence is made available. Thank you for the opportunity to share our perspective.