In a study published recently in HIV Medicine, Olalla et al.  measured ankle–brachial index (ABI) in 147 HIV-infected patients and found that 33 (22.4%) had an ‘altered’ ABI, according to the definition used by the authors (≤0.9 or ≥1.3). Thus, the prevalence of peripheral vascular disease (PAD) was much higher than in previous studies [2–4].
Whereas investigations validating ABI have found consistently that a decreased ABI (≤0.9) is a powerful predictor of death from cardiovascular causes in HIV-negative adults [5–8], the significance of high ABI (>1.40) as a predictor of atherosclerosis remains controversial, and additional non-invasive diagnostic testing is needed to diagnose PAD in that setting . Although clinical validation of ABI in patients with HIV is lacking, when ABI measurements were compared to carotid intima-media thickness (IMT), a well-established marker of sub-clinical atherosclerosis, only patients with low ABI had a high carotid IMT .
Given the usual late onset of clinical events in the course of systemic atherosclerosis, HIV clinicians would welcome disease surrogate markers. ABI is a simple, non-invasive test that may become useful for this purpose, but it should be remembered that only a low ABI (≤0.9) is a reliable indicator of systemic atherosclerosis and PAD.