Surrogate CVD outcomes not associated with immune markers in HIV-positive adults
There appears to be no significant correlation between immune markers and surrogate outcomes of cardiovascular disease (CVD) in adults with HIV, a new meta-analysis reports. While it is possible that this means a true lack of relationship, this may also be attributable to the heterogeneity of the studies.
Relevant studies were searched in PubMed, Cochrane Library and Embase. Articles published between 1996 and April 2015 were included. The meta-analysis investigated the association between immune markers and surrogate markers of CVD, excluding Carotid Intima-media thickness, in adults with HIV.
Studies that examined at least one surrogate CVD outcome in HIV patients above the age of 18 were included while those that were performed on animal systems, were not in English and involved less than 10 cases were excluded from the meta-analysis.
After the application of the inclusion and exclusion criteria, a total of 29 articles were found to be eligible for the analysis. Cumulatively, these studies describe 34 immune markers and nine surrogate outcomes for cardiovascular disease. Of the 29 studies, 27 employed a cross-sectional experimental design.
The most frequently used outcomes were coronary calcium scores (used 13 times) and flow-mediated dilation (used 10 times). Among the other outcomes were MRI scans, myocardial perfusion scintigraphy, pulse wave velocity and ankle-brachial index.
Of all the immune markers investigated across all of the studies, IL-6, sVCAM-1 and CRP were the most commonly used. Other markers were SAA, ILS, LPS and IFN-γ. Furthermore, none of the immune markers analysed showed any apparent association with any of the CVD surrogate outcomes.
Unfortunately, calculation of effect estimates was impossible as a result of the heterogeneity between studies in terms of statistical analyses employed, study populations, outcomes and immune markers investigated.
The findings show that there is no association between the surrogate outcomes of CVD and immune markers in adults with HIV. However, the heterogeneity of studies used may contribute to the uncertainty of this conclusion. More studies in the future are required to draw better conclusions.