HIV-positive women have high waist-to-hip ratios (WHR), a potential risk factor for heart disease, despite being less overweight than HIV-negative women, according to a study published in the March 1 issue of the Journal of Acquired Immune Deficiency Syndromes. Though antiretroviral drugs in general were not associated with a larger WHR, protease inhibitors were.

WHR, a measure of body composition, is calculated by comparing the circumference of the waist to the circumference of the hip. A person whose waist measures 30 inches and whose hips measure 36 inches would have a WHR of 0.83, because 30 is 83 percent of 36.

For women, a WHR of greater than 0.80 is considered to increase the risk of heart disease. However, there are two important caveats. A very slender woman with small hips would have a lower risk of heart disease than a heavy woman with a large waist size, even if they have the same WHR. Also, some women with HIV have lost fat in their hips and buttocks—including HIV-positive women with lipoatrophy—and will have a higher WHR even if their waists have not grown larger.

In order to document the impact of HIV on women’s body composition over time, Jessica Justman, MD, of the Mailman School of Public Health at Columbia University in New York City, and her colleagues examined the medical records of 942 HIV-positive and 266 HIV-negative adult female volunteers enrolled in the Women’s Interagency HIV Study (WIHS). The average age of the women was 41 years. Sixty-two percent were African American and 25 percent were Hispanic.

At the beginning of the study, the majority of the women were considered to be overweight. The average body mass index (BMI), which compares weight with height, of the women was 28 for the HIV-positive women and 29.5 for the HIV-negative women. A BMI of 25 to 29.9 is considered overweight and a BMI of 30 or more is considered obese. The average WHR of the women at study entry was also high. HIV-negative women had an average WHR of 0.88, and the HIV-positive women had an average WHR of 0.90.

Over the five years of the study, between 1999 and 2004, the BMI, waist circumference and hip circumference of the HIV-negative women increased significantly. Their WHR, however, remained stable. The exact opposite occurred in the HIV-positive women. Their BMI, and waist and hip circumference remained the same, but their WHR increased somewhat.

Factors that were associated with a higher WHR in the HIV-positive women included older age, higher CD4 count, and protease inhibitor use. African-American women were the least likely to have a higher WHR.

Because WIHS is the largest natural history study of HIV in women, Justman’s team states that the findings are significant. They conclude, however, that further research is necessary to determine whether the increased WHR in HIV-positive women actually results in an increased risk of heart disease.