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Elevated Triglycerides and Waist Circumference Predict Cardiovascular Risk for People with HIV

HIV positive people with high triglyceride levels and large girth were more likely to have other risk factors associated with cardiovascular disease and events such heart attacks, suggesting that these 2 simple measures may be used to distinguish high-risk versus low-risk individuals, according to a study in the September 22, 2011, edition of the open access journal PLoS ONE.

Several observational studies have shown that people with HIV have higher rates of cardiovascular disease than the general population, though it is not fully understood whether this is attributable to chronic HIV infection itself, associated persistent inflammation, antiretroviral drugs, or traditional risk factors in an aging population. Keeping track of all these factors to estimate cardiovascular risk can be a challenge.

Peter Janiszewski from Queen's University in Ontario, Canada, and colleagues evaluated associations between waist circumference combined with triglyceride (TG) levels and severity of lipodystrophy (abnormal body fat distribution) and cardiovascular risk among HIV positive men and women.

Although half of people with HIV will develop lipodystrophy and metabolic complications, the study authors noted as background, there is currently no simple, validated clinical screening tool to distinguish high- from low-risk individuals.

This analysis included 1481 HIV positive men and 841 women seen at the metabolic clinic of the University of Modena and Reggio Emilia in Italy between 2005 and 2009.

The mean age was about 45 years and about one-third were smokers. Participants had been on combination antiretroviral therapy (ART) for at least 18 months. Those with diagnosed abnormal blood lipid or glucose levels were on stable lipid-lowering or anti-diabetes therapy for at least 6 months. People with a history of heart attacks, strokes, or related cardiovascular problems were excluded.

Within each sex, patients were categorized into 4 groups according to waist circumference and TG levels. Various cardiovascular risk factors were assessed in the clinic after fasting overnight.

The researchers measured total and regional fat and fat-free (muscle) mass using dual-energy X-ray absorptiometry (DEXA), as well as visceral adipose tissue (VAT) and subcutaneous abdominal fat using computed tomography (CT) scans. Visceral fat surrounding the internal organs is associated with greater cardiovascular risk than subcutaneous fat under the skin.

Results

• Men with the highest TG levels and largest waist circumference had the most visceral fat (208 cm²).
• Men in this group were also most likely to have metabolic syndrome (42%) and type 2 diabetes (16%).
• The group was found to have the highest Framingham risk score (10.3) -- a standard method of estimating cardiovascular risk -- compared to the groups with lower TG levels and waist circumference (P < 0.05).
• Women in the highest TG and highest waist circumference group also had higher amounts of visceral adipose tissue (150 cm²).
• They, too, had higher prevalence of metabolic syndrome (53%) and type 2 diabetes (12.0%), as well as hypertension (31%).
• Again, these women had a significantly higher Framingham risk score (2.9) than women with lower TG levels and waist circumference (P < 0.05).

Based on these findings, the investigators concluded, "A simple tool combining waist circumference and TG levels can discriminate high- from low-risk HIV-infected patients."

For instance, they elaborated in their discussion, "HIV-infected men with both high waist circumference and high TG levels exhibited the most deleterious form of lipodystrophy, characterized by high levels of VAT combined with relatively low levels of thigh fat. Additionally, these men presented with greater deteriorations in cardiovascular health, experiencing the highest prevalence of metabolic syndrome, diabetes, hypertension, along with insulin resistance, dyslipidemia, and elevated Framingham scores."

"On the other hand, HIV-infected men and women with a low waist circumference and low TG levels appeared to be largely protected from both these body composition and cardiovascular consequences," they continued. "Thus, the present findings suggest a utility of waist circumference combined with TG levels as a simple clinical tool for discerning the severity of lipodystrophy and associated cardiovascular risk among HIV-infected men and women."

Investigator affiliations: School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada; Division of Endocrinology and Metabolism, School of Medicine, Queen's University, Kingston, Ontario, Canada; Québec Heart Institute, Hôpital Laval Research Centre, Quebec City, Quebec, Canada; Metabolic Clinic, Infectious and Tropical Disease Unit, Department of Medicine, University of Modena and Reggio Emilia, Modena, Italy.

10/11/11

Reference

PM Janiszewski, R Ross, JP Despres, et al. Hypertriglyceridemia and Waist Circumference Predict Cardiovascular Risk among HIV Patients: A Cross-Sectional Study. PLoS ONE 6(9):e25032 (free full text). September 22, 2011.