Response to: ‘Carotid intima-media thickness: assessment of sub-clinical atherosclerosis in HIV-infected patients’

We appreciate the comments from Coll and Alonso-Villaverde. As they appropriately point out, there are many reasons why the literature is not uniformly consistent with regard to the association between HIV infection, antiretroviral therapy and atherosclerosis. However, on the basis of the extensive data that exists in the area of atherosclerosis imaging, particularly with the intima-media thickness (IMT) endpoint, it is unlikely that the methodology we used for assessing carotid IMT is the major explanation for the differences among studies. Studies such as ours that have carefully controlled for known cardiovascular risk factors tend to find no association between HIV status and atherosclerosis. The matched design of our study was the first to control prospectively for major cardiovascular risk factors. We acknowledged in our discussion that the patients included in our study as a group may have been at a lower risk of atherosclerosis than those included in other reports; none had a family history of premature coronary heart disease, diabetes, or previous cardiovascular disease, and only 22% were current smokers. This is a new area of investigation and all possibilities need to be determined, including potential differences in the atherothrombotic clinical event with only marginally detectable differences in atherosclerosis. Our study has recently concluded 96 weeks' of follow-up. As we proceed with the final analysis of our study, we will examine the differences among groups in the rate of progression of carotid IMT. The progression of subclinical atherosclerosis among the different groups of participants may be more revealing than discerning differences cross-sectionally. As concerns the issues surrounding the use of protease inhibitors and atherosclerosis, it is imperative that this relationship is well understood and that prospective studies are conducted before public health statements are made about whether these agents are atherogenic, because these are evidence-based life-saving medications for patients with HIV infection.