HIV-infected women have increased risk factors for the development of cardiovascular disease, United States researchers warn in the 1st May edition of The Journal of Acquired Immune Deficiency Syndromes. They report that most of these risk factors may be influenced primarily by abnormal body fat redistribution, rather than being a direct consequence of HIV infection or treatment.
HIV infection and antiretroviral therapy are known to increase the risk of cardiovascular disease and to cause changes in body fat distribution, such as loss of fat from under the skin and increases in fat accumulation around the internal organs. This information was gathered from studies that included few women, leaving uncertainty surrounding whether these conclusions apply equally to both sexes.
To redress this imbalance, investigators from Boston compared cardiovascular risk factors and body fat levels in 100 HIV-positive and 75 HIV-negative women recruited from hospital and community-based health care providers in Massachusetts. The two groups of women were similar in age, weight and racial composition.
“This study demonstrates marked abnormalities in inflammatory and traditional cardiovascular disease risk indices in HIV-infected women,” they conclude. “Simple measures of body composition such as waist-to-hip ratio are strongly associated with abnormal biochemical indices in this population.”
The researchers measured levels of a range of chemical markers in the blood of the women, including traditional risk factors for cardiovascular disease, such as blood fat, glucose and insulin levels. They also assessed the levels of the newly discovered factors that are linked to inflammation of the blood vessels, including C-reactive protein (CRP), interleukin-6 (IL-6) and adiponectin.
Levels of triglyceride fats in the blood were higher in the HIV-positive women (mean 1.84 vs. 0.85 mM, p
The HIV-positive women also had higher levels of insulin after an overnight fast (81 vs. 45 pM, p
Levels of high-density lipoprotein (HDL, or ‘bad’) cholesterol were lower in the women with HIV (1.17 vs. 1.34 mM, p
The HIV-positive women also had altered levels of the inflammatory markers, with elevated levels of CRP (4.6 vs. 2.3 mg/l, p = 0.007) and IL-6 (2.7 vs. 1.8 pg/ml, p = 0.02). These are both linked to an increased risk of cardiovascular disease. Although there were differences in the use of hormone replacement therapy and smoking between the two groups of women, the investigators found that controlling for these factors did not influence their results.
They also had lower levels of adiponectin (5.4 vs. 7.6 mg/l, p
The researchers went on to assess the amount of body fat in the women using simple measurements of waist and hip circumference and by carrying out computerised tomography (CT) and dual-energy X-ray absorptiometry (DEXA) scans.
They found that the HIV-positive women had more fat around the internal organs than the HIV-negative controls (103 vs. 71 cm2, p = 0.001) and less fat under the skin (244 vs. 280 cm2, p = 0.05), as has previously been observed in HIV-infected men.
The ratio of the distance around the waist to the distance around the hips (waist-to-hip ratio) was also higher in the women with HIV (0.92 vs. 0.83, p
The researchers used ‘stepwise regression’ analysis to assess whether these measures of body composition were related to the biochemical risk factors in the HIV-positive women. They found that waist-to-hip ratio was strongly associated with most of the risk factors, including CRP (p = 0.008), adiponectin (p = 0.004) and fasting insulin levels (p
Use of antiretroviral therapy and individual antiretroviral agents were not associated with any of the risk factors measured. Eighty-one per cent of the HIV-positive women in the study were taking antiretroviral therapy.
Waist-to-hip ratio was also linked to the biochemical risk factors in the HIV-negative women. However, when they analysed their data for all women together, the investigators found that HIV infection only had a significant additional effect on glucose, triglyceride and HDL cholesterol levels.
This led them to conclude that most of the cardiovascular risk factors observed are due to changes in body fat distribution, and are not a direct consequence of HIV infection or treatment. “Although causality and sequence cannot be definitively determined in a cross-sectional study, our data strongly suggest that the changes in body composition associated with highly active antiretroviral therapy, not the medication use itself or HIV status, contribute to abnormal cardiovascular disease risk among HIV-infected women,” they write.
“Further studies are critically needed to determine whether increased cardiovascular risk indices translate into increased cardiovascular events among HIV-infected women. In addition, treatment strategies to modify cardiovascular disease risk and improve abnormal fat distribution are needed.”
Dolan SE et al. Increased cardiovascular disease risk indices in HIV-infected women. J Acquir Immune Defic Syndr 39: 44 – 54, 2005.