Lipoatrophy, or fat loss, usually in the face, limbs, or buttocks, is a common finding in people with HIV, especially those taking certain antiretroviral drugs. Subtle fat loss may start before visible changes become apparent, and how best to determine the extent of lipoatrophy in HIV patients is not well understood.

In the current study, published in the January 9, 2009 advance online edition of AIDS Patient Care and STDS, researchers evaluated the use of ultrasound for assessing lipoatrophy in 151 HIV-infected Caucasian patients (79% men) in Zagreb, Croatia, who had received antiretroviral therapy for at least 1 year. Half of the participants acquired HIV through heterosexual contact and 42% though sex between men.

Ultrasound was used to measure subcutaneous fat thickness of the cheeks, arms, and legs. The researchers determined the sensitivity and specificity of ultrasound as a diagnostic tool for lipoatrophy using receiver-operating characteristic curves, using patient and clinician assessment as their reference for the presence of lipoatrophy.

The fat layer of skin is located in the subcutaneous layer of tissue called the hypodermis. The thickness of the fat layer depends on the size and number of fat cells.

Results

The mean CD4 cell count at study entry was 503 cells/mm3.

77 participants (51%) had been treated with stavudine (d4T; Zerit) and 91 (64%) with a protease inhibitor for at least 6 months.

19 participants (13%) had lipoatrophy in at least 1 anatomic site.

Sensitivity of ultrasound ranged from 67% to 71%.

Specificity ranged from 65% to 71%.

Positive and negative predictive values of ultrasound ranged from 11% to 20% and from 96% to 97%, respectively.

Ultrasound-diagnosed lipoatrophy was more frequently found in women and in patients with a history of stavudine use.

Patients with lipoatrophy had a longer overall duration of antiretroviral therapy than those without lipoatrophy.

The authors concluded that ultrasound is a useful tool in ruling out the presence of clinical lipoatrophy in patients on combination antiretroviral therapy. "Using this objective measure of subcutaneous fat may be useful in helping clinicians make decisions about changing therapy," wrote the authors.

University Hospital for Infectious Diseases, University of Zagreb Medical School, Zagreb, Croatia; School of Medicine, University of California, San Francisco, CA; Biometrika Healthcare Research, Zagreb, Croatia; School of Medicine and Global Health Sciences, University of California, San Francisco, CA; University Hospital "Sisters of Mercy," University of Zagreb, Zagreb, Croatia.

1/23/09

Reference
K Viskovic, I Richman I, K Klasnic, and others. Assessment of Ultrasound for Use in Detecting Lipoatrophy in HIV-infected Patients Taking Combination Antiretroviral Therapy. AIDS Patient Care and STDS 23(2). January 9, 2009 [Epub ahead of print]