Background: The impact of HIV infection on atherosclerosis has not yet been fully investigated. We investigated the relationship between HIV status and early ultrasonic atherosclerosis signs in a 1:4 case-control design in the context of conventional vascular risk factors.

Methods: We assessed the individual risk factors for atherosclerosis, blood pressure (BP), cholesterol levels and measured intima media thickness (IMT) of the carotid artery system by B-mode ultrasound in 292 consecutive HIV patients. The findings were compared to randomly selected 1168 control individuals from the Carotid Atherosclerosis Progression Study (CAPS), who were matched for age and sex.

Results: The first positive HIV test among the positive patients was in median 10.6 years ago from IMT assessment (95%CI. +/- 5.2y), CDC-class B (40%) was more frequent than C (28%), mean CD4 cell count was 439/µL (95%CI: +/- 243) and most patients were virologically suppressed (74.7% <400copies/mL or 49.3% <20copies/mL). Controls were significantly more obese (BMI 27.5 vs. 25.1), had higher cholesterol levels (5.87 vs. 5.41mmol/L), systolic (131.7 vs. 122.8mmHg) and diastolic (81.1 vs. 75.0mmHg) BP. HIV patients were taking significantly more antihypertensive (14.4% vs. 10.6%) and lipid lowering (18.5% vs. 5.1%) drugs, as was cigarette smoking (27.0 vs. 14.2 pack years).

In HIV positive individuals, internal carotid artery plaques were significantly more common (12.3% vs. 7.8%, p=0.0312) in unadjusted models. The common carotid IMT was 5.0% (95% confidence interval: [2.3, 7.8%], p=0.0002) or 0.036mm [0.012, 0.060mm] (p=0.0034) higher in HIV positives when adjusted for multiple risk factors. In the carotid bifurcation, the IMT values were 19% [14, 24%] or 0.180mm [0.123, 0.238mm] higher in HIV patients (p<0.0001), respectively. This effect was not significant for internal carotid IMT, but showed a trend (IMT 4.3% [-0.7, 9.5] or 0.037mm [-0.016, 0.089] higher, p=0.0905 or 0.1721).

Conclusions: The data from this study suggests long-term HIV infection may be an independent risk factor for early atherosclerosis as measured by ultrasonic IMT assessment. Assuming a similar risk-ratio would be found in large population-based trials, the observed IMT elevation suggests that vascular risk is 4-14% and the 'vascular age' is 4-5 years higher in HIV-positive subjects. Further studies are warranted to find an approach to specific pathophysiology and to evaluate the role of HIV-specific medication.