Waist circumference and triglycerides: simple measures of increased cardiovascular risk for patients with HIV

Measuring waist circumference and triglyceride levels may be an easy way of identifying which HIV-positive patients have an increased risk of cardiovascular disease, according to research published in PLoS One.

Italian investigators found a consistent and significant relationship between the two measures and the risk factors of cardiovascular disease in HIV-positive men and women.

Some older HIV therapies were associated with changes in body fat composition known as lipodystrophy. The syndrome includes the accumulation of visceral adipose fat and/or fat wasting for the face, limbs, and buttocks. The investigators note that these body fat changes have been associated with “the classic constellation of cardiovascular risk factors.” Indeed, cardiovascular disease is an increasingly important cause of serious illness and death in patients with HIV.

However, only a minority of HIV-positive patients develop lipodystrophy and its associated cardiovascular complications. “Therefore,” suggest the investigators, “there exists an unmet need for a simple yet accurate clinical tool to discern the high-risk from the low-risk HIV-infected patient.”

A combination of elevated waist circumference and triglycerides – known as the hypertriglyceridemic waist phenotype – has been used for over a decade to identify HIV-negative patients with an increased risk of cardiovascular disease.

The investigators therefore designed a cross sectional study involing 2322 patients, 841 of whom were women, who received care at an HIV metabolic clinic between 2005 and 2009.

Triglyceride levels were monitored using blood tests and the patients’ waist circumference was measured. In addition, DEXA scans were used to assess the patients’ regional fat and fat free mass, and visceral adipose tissue and abdominal subcutaneous fat was measured using CT scanning.  .

Waist circumference was classified as high if it was above 90 cm in men and 85 cm in women. The cut off point for high triglycerides was 2.0 mmol/l for men and 1.5 mmol/l for women.

The patients were placed into once of four categories:

• Low waist circumference/low triglycerides.
• Low waist circumference/high triglycerides.
• High waist circumference/low triglycerides.
• High waist circumference/high triglycerides.

Investigators then explored the relationship between waist circumference and triglycerides and a number of factors associated with an increased risk of cardiovascular disease, such as Framingham risk score, hypertension, metabolic syndrome, and type-2 diabetes.

Overall, 27% of men and 20% of women had a high waist circumference accompanied by high triglycerides, and these patients were significantly older and less physically active (p < 0.05) than patients in the other groups.

After controlling for these differences in age and exercise levels, the investigators found a consistent relationship between high waist circumference/high triglycerides and cardiovascular risk factors in men.

For example, the prevalence of metabolic syndrome was significantly higher among men in the high waist circumference/high triglycerides than all other groups (48% vs 4-32%; p < 0.05). Similarly, prevalence of type-2 diabetes was elevated (16% vs 6-7%; p < 0.05), and men with high waist circumference/high triglycerides also had a higher Framingham risk score than men in the other three groups (10 vs 5.8-9.5; p < 0.05).

Prevalence of cardiovascular risk factors was significantly higher for women in the high waist circumference/high triglycerides group.

Women in this category were more likely to have metabolic syndrome (56% vs 2-26%; p < 0.05), diabetes (12% vs 4%; p < 0.05), hypertension (31% vs 14%; p < 0.05), and also a higher Framingham score (2.9 vs 1.5; p < 0.05) than women in the other categories.

“The combination of waist circumference and triglycerides was shown to discriminate high-risk and low-risk HIV-infected men and women,” write the authors, “the present findings suggest a utility of waist circumference combined with triglyceride levels as a simple clinical tool for discerning the severity of lipodystrophy and associated cardiovascular risk.”

HIV treatment history and nadir CD4 cell count did not affect these findings.

There was also a high prevalence of the mixed form of lipodystrophy (58% and 64%) in both men and women with high waist circumference/high triglycerides.

The investigators conclude, “these findings suggest that a waist circumference above 90 cm and triglycerides above 2.0 mmol/l among HIV-infected men and a waist circumference above 85 cm and triglycerides above 1.5 mmol/l among HIV-infected women discriminates the high from the low-risk patient in terms of body composition as well as cardiovascular risk.”

Janiszewski PM et al. Hypertriglyceridemia and waist circumference predict cardiovascular risk among HIV patients: a cross-sectional study. PloS One, 6(9): e25032, doi:10.1371/journal.pone.0025032, 2011 (click here for the open-access article).